RPGBOT - DnD 5e - The Barbarian Handbook

DnD 5e - The Barbarian Handbook

Last Updated: March 17th, 2020

Disclaimer

I will use the color coding scheme which has become common among Pathfinder build handbooks, which is simple to understand and easy to read at a glance.

Red: Bad, useless options, or options which are extremely situational.
Orange: OK options, or useful options that only apply in rare circumstances.
Green: Good options.
Blue: Fantastic options, often essential to the function of your character.

I will not include 3rd-party content, including content from DMs Guild, even if it is my own, because I can't assume that your game will allow 3rd-party content or homebrew. I also won't cover Unearthed Arcana content because it's not finalized, and I can't guarantee that it will be available to you in your games.

Introduction

Barbarians are all about getting angry and dealing damage. They have a ton of hit points, resistance to damage, and Rage gives a wonderful bonus to damage. Barbarians don't get much in the way of skills, so generally they're stuck as combat monsters, but they function equally well as a Defender and a Striker.

After reading this handbook, I encourage you to read my Barbarian Subclasses Breakdown.

Barbarian Class Features

Hit Points: d12 is the biggest hit die available.

Saves: Strength saves are fairly rare, but Constitution saves are common and typically very problematic.

Proficiencies: Medium armor and martial weapons will get you a long way, but you get no tool proficiencies, and only two skills.

Rage: Rage is the Barbarian's defining class feature. The bonus damage isn't huge, but it's reliable and consistent. The resistance to damage makes Barbarians exceptionally durable. You can rage multiple times in the same encounter if you absolutely need to, but your number of rages per day is limited, so try not to do so if you can avoid it.

Unarmored Defense: This is great flavor for the Barbarian, but won't do much good for you unless your abilities are very high. Your Dexterity and Constitution modifiers need to total +7 to match the total AC bonus provided by half plate armor. That's generally achievable by level 8 unless you rolled for ability scores, and assuming that you started with 14 Dexterity and largely ignored Strength. More realistically, you should expect to hit 20 Constitution by 12th level, and even then Unarmored Defense will only break even with Half plate. If magic armor is an option you'll need to put an ability increase into Dexterity before you have a good reason to drop your armor.

Reckless Attack: Rage makes you resistant to damage from normal weapons (Magical weapons which do weird damage types still work fine), so advantage on attacks against you doesn't matter as much. Go crazy. Kill all of the things.

Danger Sense: In medium armor your dexterity probably isn't fantastic, but advantage on any save is fantastic.

Primal Path: See me Barbarian Subclasses Breakdown.

Extra Attack: Two attacks means potentially twice as much damage in a turn, and twice as much opportunity to apply your rage bonus to damage.

Fast Movement: Amusing, but not game-changing.

Feral Instinct: You are basically immune to surprise attacks. Advantage on initiative will allow you to go first frequently, so be sure to get into position to keep enemies from reaching your squishy allies.

Brutal Critical: Critical hits are very rare, and this makes it difficult to use a Maul effectively.

Relentless Rage: This will keep you conscious for a long time if you get hit with a low numbers of high-damage attacks, but lots of small attacks will raise the DC too quickly for this to remain effective. Be sure to eliminate weak but numerous enemies before your HP starts getting scary.

Indomitable Might: By now you might very easily have 20 Strength, so you're guaranteed to get a ridiculously high roll on any Strength check. Remember that saves and attacks aren't checks, so you still need to roll high on those.

Primal Champion: The equivalent of 4 ability increases all at once. Your abilities should be absurd by this point, so now may be a good time to abandon your armor in face of running around slaying monsters in your undergarments.

Abilities

Barbarians are all about their physical ability scores. If your scores are good enough you can forgo armor, so it's nice to have adequate Dexterity and Constitution to beat the AC bonus provided by half plate.

Str: Barbarians are all about lots of Strength and big weapons, so Strength should almost always be your best ability.

Dex: 14 Dexterity is great to boost your AC with half plate. If you prefer to go armor-less, look for an item to boost your Dexterity so that you can spend your ability increases on Strength and Constitution.

Con: Second only to Strength. Barbarians take a lot of damage, so you need all the hit points you can get. Constituion also powers Unarmored Defense.

Int: Dump stat. Intelligence saves are very rare, and Barbarians don't get any Intelligence-based skills.

Wis: Wisdom saves are common, so don't dump it, but don't put a ton of effort into improving it.

Cha: Charisma only matters for a couple of the Barbarian's skills, and for the Berserker's Intimidating Presence. If you went for Totem Warrior and didn't pick up Intimidation, you can dump Charisma and use the points to boost your Wisdom.

Point Buy	Standard Array
Str: 15 Dex: 14 Con: 14 Int: 8 Wis: 10 Cha: 10	Str: 15 Dex: 13 Con: 14 Int: 8 Wis: 12 Cha: 10

Races

Look for bonuses to Strength and medium size so that you can effectively use big weapons like a Greataxe.

Aarakocra^EEPC: Flight is fantastic, but the Aarakocra's abilities don't work well for a Barbarian.

Aasimar^VGTM: Charisma won't do much for a barbarian.

Fallen: Tempting, but almost all of the useful stuff is from the subrace.
Protector: Access to flight is tempting, but you can get that from other places.
Scourge: Interesting, but you need a Strength bonus more than a Constitution bonus.

Bugbear^VGTM: Dexterity might not seem like an obvious benefit for a barbarian, and it's not as good as Constitution, but the AC bonus is still helpful. Reach makes it easy to compete with larger creatures or attack smaller foes at a distance, and Sneaky allows you to be an ambush predator.

Dragonborn^PHB: A bonus to Strength is great, but the bonus to Charisma is wasted unless you want to use Intimidating Rage a bunch. The Dragonborn's breath weapon is helpful for handling groups of weak enemies which a Barbarian would normally need to wade through one or two at a time.

Dwarf: Most of the Dwarf's racial traits are wasted on the Barbarian, but the Constitution bonus is great and Darkvision is always welcome. The Dwarven Fortitude racial feat can be a great way to keep yourself alive in combat if your AC is low and you don't have healing readily available.

Duergar^SCAG: In a subterranean campaign, this is at least on par with Mountain Dwarf. Otherwise, sunlight sensitivity is a huge problem.
Hill^PHB: A bonus to wisdom is nice, but not going to make a big difference. The bonus hit points is also helpful, but you already have a d12 hit die and a Constitution bonus from the general Dwarf traits.
Mountain^PHB: A bonus to Strength on top of the Dwarf's bonus to Constitution is perfect for a Barbarian.

Elf^PHB: A bonus to Dexterity isn't as helpful as one to Strength or Constitution, but the Elf's other racial traits are great for the Barbarian. Darkvision is excellent, and Keen Senses saves you a skill choice.

Drow: Nothing helpful for the Barbarian.
Eladrin^MToF: Fey Step is really good, but that's the only appeal.
High Elf: Nothing helpful for the Barbarian.
Sea Elf^MToF: +1 Constitution is the only thing you need from the Sea Elf.
Shadar-Kai^MToF: Dexterity and Constitution isn't ideal for a barbarian, but your AC will be really good, and you get a damage resistance and the ability to teleport.
Wood Elf: A wisdom bonus might help with your Wisdom saving throw, but that's about it.

Firbolg^VGTM: A bit too tricksy and indirect for a Barbarian.

Genasi^EEPC: Bonus Constitution isn't as good as Strength, but it boosts the Barbarians AC and hit points, both of which are important.

Air: Dexterity isn't particularly important for Barbarians, and the ability to hold your breath is extremely situational.
Earth: Bonus Strength, and the ability to move across difficult terrain unimpeded helps you to get into melee in situations where it's normally difficult to do so.
Fire: Intelligence is for Wizards. The resistance to fire is tempting, and Produce Flame is a decent option, but the spells don't really play to the Barbarian's strengths.
Water: Wisdom is a good defensive ability, and the spells are excellent utilities. Resistance to Acid is nice, but situational.

Gith: Githyanki are great, Githzerai are terrible and you should ignore them.

Githyanki^MToF: +2 Strength, some extra proficiencies, and Giyhtanki Psionics gives you some magic options to overcome problems that many barbarians can't handle.
Githzerai^MToF: Nothing helpful for Barbarians.

Gnome: Nothing helpful for the Barbarian.

Deep (Svirfneblin)^{EEPC / SCAG}: Dexterity and stealth abilities aren't useful for Barbarians.
Forest^PHB: Nothing helpful for the Barbarian.
Rock^PHB: The constitution bonus helps, but it's not nearly enough to make the Gnome viable for a Barbarian.

Goblin^VGTM: Nothing helpful for the Barbarian.

Goliath^VGTM/EEPC: Tailor-made to be a melee Monster. Bonuses to your important abilities, free Athletics proficiency, and Stone's Endurance adds a pile to your effective daily hit point total.

Half-Elf: Several of the half-elf variants are good choices, and if you want to excel at Intimidation half-elf is the way to go. Otherwise, the Mountain Dwarf and Variant Human will be better at killing things.

Aquatic^SCAG: Only if you're in an aquatic campaign.
Drow^SCAG: The spells are decent, and Faerie Fire presents a way to handle invisible foes which Barbarians normally can't handle, but you'll have trouble using Dancing Lights and Darkness.
High/Moon/Sun^SCAG: Weapon training is redundant, and Barbarians won't get much use out of a cantrip. You might consider green flame blade, but you'll have better damage output from relying on conventional attacks.
Keen Senses^SCAG: The sidebar describing half-elf variants specifices that you can take Keen Senses in place of Skill Versatility, or a trait based on your elf parentage. Keen Senses give you a single fixed skill, and you're giving up proficiency in any two skills. It should be immediately apparent that this is a terrible trade.
Wood^SCAG: Weapon training is redundant and Mask of the Wild won't be useful without Stealth proficiency, but Fleet of Foot is great if you want to be the world's fastest Barbarian
Vanilla^PHB: Two skills can get you quite a lot. Coupled with the Half-elf Charisma bonus you could easily be your party's Face.

Half-Orc^PHB: The Half-Orc is tailor-made for the Barbarian. Bonuses to Strength and Constitution are essential, Darkvision is great, and you save a skill choice on Intimidate. The Half-Orc's other abilities match some of the Barbarian's class features, but it appears that they work together, so you can essentially double-down on Brutal Critical and Relentless Rage. The Prodigy racial feat is excellent if you plan to use Athletics for grappling. The Orcish fury racial feat is tempting with a greataxe, but probably not worth the feat.

Halfling^PHB: A dexterity bonus is okay for Barbarians, but small size is a problem because you can't use big weapons like a Greataxe.

Ghostwise^SCAG: Nothing helpful for the Barbarian.
Lightfoot^PHB Nothing helpful for the Barbarian.
Stout^PHB A small Constitution bonus, and resistance to poison. Like a small dwarf.

Hobgoblin^VGTM: The Consitution bonus and Saving Face are both great, but that's really the only thing that the barbarian can use.

Human^PHB: Versatile and fantastic at everything. The Prodigy racial feat is excellent if you plan to use Athletics for grappling.

Vanilla: Barbarians really only need two ability scores, but a +1 to all of your scores can be helpful if you use the point buy ability generation method to give yourself low, odd-numbered base abilities to save points.
Variant: You still get crucial bonuses to your Strength and Constitution, and you can get an awesome feat at level 1. Great Weapon Master seems like an obvious choice, but remember that at low level a -5 penalty to your attacks is crippling, so you may want to save it for higher levels when you can more easily handle that penalty. The bonus skill won't see a lot of use.

Kenku^VGTM: Nothing helpful for the Barbarian.

Kobold^VGTM: Strength penalty.

Lizardfolk^VGTM: Natural Armor and the lizardfolk's Constitution increase conflict a bit on a barbarian because Unarmored Defense and Natural Armor both provide alternatives to conventional armor, but the lizardfolk still makes a fun barbarian.

Locathah^LR: Similar to the Bugbear in terms of ability increases, but not quite as useful. The natural armor is wasted unless you have less than 14 Consitution, which is a terrible idea.

Orc^VGTM: Aggressive is cool, but the half-orc is considerably better than the full orc. If you still want to play a full-blooded Orc, ask your DM if you can use the Eberron version because it's a much better-written race.

Tabaxi^VGTM: Nothing helpful for the Barbarian.

Tiefling: Nothing helpful for the Barbarian.

Asmodeus^MToF: Nothing helpful for Barbarians.
Baalzebul^MToF: Nothing helpful for Barbarians.
Dispater^MToF: Nothing helpful for Barbarians.
Fierna^MToF: Nothing helpful for Barbarians.
Glasya^MToF: Nothing helpful for Barbarians.
Levistus^MToF: Nothing helpful for Barbarians.
Mammon^MToF: Nothing helpful for Barbarians.
Mephistopheles^MToF: Nothing helpful for Barbarians.
Zariel^MToF: Legacy of Avernus has some neat spells, and the Strength increase is nice, but that's not enough to make this a useful option.
Variant: Feral^SCAG: Bad ability spread.
Variant: Devil's Tongue^SCAG: Nothing helpful for Barbarians.
Variant: Hellfire^SCAG: Nothing helpful for Barbarians.
Variant: Vanilla^PHB: Nothing helpful for Barbarians.
Variant: Winged^SCAG: Nothing helpful for Barbarians.

Tortle^TP: +2 Strength and 17 natural armor is fantastic for a Barbarian. With a solid source of AC, you don't need to worry about Dexterity, especially at low levels before you've picked up multiple Ability Score Increases. Survival proficiency is nice, too.

Triton^VGTM: The ability increases are decent, but the triton's other racial traits don't do much for the barbarian.

Verdan^AcInc: +1 Constitution is not enough, and Black Blood Healing is less effective with larger hit dice..

Yuan-Ti Pureblood^VGTM: Nothing helpful for the Barbarian.

Setting-specific races are address below. Not every setting allows every race, and while most races presented in the core rules and in content for the Forgotten Realms can be used in other settings, races specific to settings like Ravnica aren't typically allowed in other settings. Talk to your DM about what races are allowed in your game.

Races of Eberron

Bugbear^ERLW: See above.

Changelings^ERLW: Bad ability spread.

Goblin^ERLW: See above.

Elf^ERLW: Eberron's elves are mostly the same as core elves, but include some additional subraces.

Aerani High: Trade the core High Elf's Weapon Training trait for expertise in a single skill or tool of your choice.
Aerani Wood: Trade the core Wood Elf's Weapon Training trait for expertise in a single skill or tool of your choice.
Valenar Wood: Trade the core Wood Elf's Weapon Training trait for slightly different weapon proficiencies, including the double scimitar. If you already get proficiency with martial weapons it doesn't matter, and if you don't you might prefer the original set of weapons because they include short swords. The two sets are roughly equivalent, so use whichever you like (or whichever your DM allows).

Hobgoblin^ERLW: See above.

Orc^ERLW: The Eberron version of the Orc drops the Intelligence increase, and replaces Menacing with two skills from a fixed list. This makes the Orc considerably more interesting, but I think the Half-Orc is still more effective in combat. If you need more skills the Eberron Orc is a great option, but otherwise stick to the Half-Orc.

Kalashtar^ERLW: Bad ability spread. Resistance to psychic damage is near because it means that while raging you're resistant to all damage, but that is not enough to make this workable.

Shifter^ERLW: Darkvision is great, and some of the Shifter options work for the barbarian conceptually, but you may have trouble combining Shifting and Rage since both are activated as a Bonus Action. At low levels Shifting can provide a useful alternative while your number of Rages is small, and even once you can comfortably rage during every fight you may find that in some situations it helps to use Shifting before you use Rage so that your Temporary Hit Points can absorb some damage while you get yourself up and running.

Beasthide: Perfect ability score increases, proficiency in an important skill, extra Temporary Hit Points, and you get +1 to AC while shifting so you're even more durable.
Longtooth: While Dexterity isn't quite as nice as Constitution, it's still somehwat helpful. Intimidation isn't a good skill for the barbarian, but that's not the draw here. The ability to bite as a bonus action means that you get as many attacks a chatacter using two-weapon fighting without giving up a shield or a two-handed weapon. Extra attacks means more opportunities to apply your growing damage bonus from Rage.
Swiftstride: Bad ability spread.
Wildhunt: Bad ability spread.

Warforged^ERLW: Increase Constitution, a flexible increase which goes into Strength, +1 AC, some resistances and immunities, and no need to sleep. A great formula for a simple, durable barbarian. Be sure to pick up proficiency in Perception to capitalize on the fact that you don't need sleep so that you can remain alert and watch over your party during long rests.

Dragonmarks

While the design intent for Dragonmarks was that they would offer some innate spellcasting for everyone, every dragonmark includes an expanded spell list which is arguably a more significant benefit than most of the provided racial traits. Because the expanded spell options are such an important part of the dragonmarks, if you're not playing a spellcaster you're giving up a huge part of your racial traits, which makes it exceptionally difficult to justify playing a dragonmark character who can't cast spells.

Dragonmarked Dwarf^ERLW: Dragonmark traits replace your subrace.

Mark of Warding: Bad ability spread.

Dragonmarked Elf^ERLW: Dragonmark traits replace your subrace.

Mark of Shadow: Bad ability spread.

Dragonmarked Gnome^ERLW: Dragonmark traits replace your subrace.

Mark of Scribing: Bad ability spread.

Dragonmarked Half-Elf^ERLW: Dragonmark traits replace some of your normal racial traits, as described in the entry for each Dragonmark.

Mark of Detection: Bad ability spread.
Mark of Storm: Bad ability spread.

Dragonmarked Half-Orc^ERLW: Dragonmark traits replace ALL of your racial traits.

Mark of Finding: Bad ability spread.

Dragonmarked Halfling^ERLW: Dragonmark traits replace your subrace.

Mark of Healing: Bad ability spread.
Mark of Hospitality: Bad ability spread.

Dragonmarked Human^ERLW: Dragonmark traits replace ALL of your racial traits.

Mark of Finding: See Mark of Finding under Dragonmarked Half-Orc, above. Mechanically, the final racial traits are identical.
Mark of Handling: A flexible increase means that you can get a crucial Strength increase, but there isn't enough here that's appealing to the Barbarian. If your DM will let you explore training creatures outside of your class features to get things like a griffon mount this might be more useful, but mounts are generally far too frail to be useful in combat, and even if they weren't that's a big assumption to make of your DM.
Mark of Making: Bad ability spread.
Mark of Passage: Strength and Dexterity work fine for the Barbarian, and Magical passage is really useful for a class so totallybereft of magic options, but that's all that we care about and that's simply not enough.
Mark of Sentinel: An interesting possibility for a tanky barbarian focused on defending their allies, but you'll lag offensively by a hug emargin, and this isn't nearly as interesting without the ability to cast spells.

Races of Ravnica

Centaur^GGTR: The Strength increase is a great start, and Charge is fantastic on a barbarian. If you rage before charging, the hoof attack is an extra opportunity to apply your Rage bonus to damage, not to mention your crazy Strength bonus.

Goblin^GGTR: See above.

Loxodon^GGTR: The Constitution increase is great, but Natural Armor will hopefully be overridden by Unarmored Defense, and the Loxodon has very little else to contribute to the Barbarian.

Minotaur^GGTR: Minotaurs are absolutely perfect barbarians. The ability increases are fantastic. Goring Rush gets you the most important part of the Charger feat, and Hammering Horns gets you the most important part of the Shield Master feat without requiring a shield.

Simic Hybrid^GGTR: With the flexible ability increase in Strength, the Simic Hybrid is an interesting and versatile option for the Barbarian. The first round of Animal Enhancement gets you some utility options which the Barbarian has no way to replicate, and the second offers several appealing combat options which will nicely complement your class features.

Vedalken^GGTR: Nothing helpful for the Barbarian.

Races of Wildemount

Aarakocra^EGtW: See above.

Aasimar^EGtW: See above.

Bugbear^EGtW: See above.

Dragonborn: Wildemount presents two new Dragonborn variants, each replacing the standard Dragonborn's ability score increases and damage resistance.

Draconblood^EGtW: Bad ability spread.
Ravenite^EGtW: Better ability scores for the Barbarian than the standard Dragonborn, and you can survive without the Dragonborn's damage resistance. Ravenite adds Darkvision, a Constitution increase, and Vengeful Assault which offers an occasional boost to your damage output..
Standard^PHB: See above.

Elf^EGtW: Wildemount elves share the core traits of core elves, but Wildemount adds two new elf subraces. See above for information on core elf traits.

Pallid Elf: Nothing useful for the Barbarian.
Sea Elf: See above.

Firbolgs^EGtW: See above.

Genasi^EGtW: See above.

Goblin^EGtW: See above.

Halfling^EGtW: Wildemount halflings share the core traits of core halflings, but Wildemount adds a new halflings subrace. See above for information on core halflings traits.

Lotusden: Nothing useful for the Barbarian.

Hobgoblin^EGtW: See above.

Goliath^EGtW: See above.

Kenku^EGtW: See above.

Orc^EGtW: See above, under "Races of Eberron". Wildemount uses the updated Orc racial traits rather than the original traits published in Volo's Guide to Monsters.

Tabaxi^EGtW: See above.

Tortle^EGtW: See above.

Skills

Animal Handling (Wis): Not really helpful for the function of the Barbarian, but the flavor makes sense.
Athletics (Str): The only Strength-based skill, Athletics is more than climbing and swimming. You use Athletics for grappling and for pushing enemies, both of which can be excellent options for Barbarians.
Intimidation (Cha): If you're built with a bit of Charisma for the Berserker's Intimidating Presence, you can be good at Intimidate. Otherwise, skip it.
Nature (Int): Intelligence is a dump stat for Barbarians, but if no one in the party has access to Nature it's not an awful choice.
Perception (Wis): One of the most important skills in the game. At least two people in the party should have it, but more is always better.
Survival (Wis): Adventuring tends to involve a lot of wandering around in untamed wilderness, so Survival can be very helpful to your party.

Background

This section does not address every published background, as doing so would result in an ever-growing list of options which don't cater to the class. Instead, this section will cover the options which I think work especially well for the class, or which might be tempting but poor choices. Racial feats are discussed in the Races section, above.

Barbarians can't do a lot with skills, but what skills you do want are on the Barbarian skill list. When looking for a Background, try to pick up skills which complement your existing skill proficiencies and which capitalize on your ability scores.

City Watch^SCAG: Athletics is great, but you won't get much use from Insight or the ability to speak two languages with your garbage Charisma.
Criminal^PHB: This might work for a Wolf Totem Barbarian, especially if you have a Rogue in the party who can be stealthy with you.
Folk Hero^PHB: Two skills from the Barbarian skill list, and a couple of tool proficiencies. The theme works really well for a Barbarian who made a name for himself among his tribe, then set out to do some more heroics.
Hermit^PHB: Medicine and herbalism can be useful for a Barbarian, especially if you don't have a healer in the party.
Outlander^PHB: The go-to option for Barbarians, you get two skills from the Barbarian list, and some fun stuff like proficiency with a musical instrument which you will never use.
Sailor^PHB: Great for aquatic campaigns. Two good skills from the Barbarian list, and boats!
Soldier^PHB: Somewhere between the Folk Hero and the Outlander. Two good skills from the Barbarian skill list, and some fun tool proficiencies.
Uthgardt Tribe Member^SCAG: Two important Barbarian skills, but instruments, artisan's tools, and languages are generally wasted on the Barbarian.

Feats

This section does not address every published feat, as doing so would result in an ever-growing list of options which don't cater to the class. Instead, this section will cover the backgrounds recommended in the "Quick Build" section of the class description, as well as other backgrounds which I think work especially well for the class, or which might be tempting but poor choices. The possibility of custom backgrounds also means that it is literally impossible for me to provide comprehensive analysis of every potential background in existence.

Alert^PHB: Feral Instinct does plenty on its own, so you shouldn't need this.
Charger^PHB: Great for closing to melee, but situational. If you can't get into melee range with your movement it may be better to use your action to throw some javelins.
Dual Wielder^PHB: Two-Weapon Fighting can be a good way to bring your bonus Rage damage into play more frequently, but since Two-Weapon Fighting uses your bonus action, this is a bad option for Berserker Barbarians.
Durable^PHB: Rage gives you resistance to most weapon damage, but you'll still face problems from spells, and with only medium armor the Barbarian's hit points typically rise and fall very far very quickly. Magical healing goes a long way, but much of your healing will come from your Hit Dice. Ideally your Constitution will be high enough to give you a big pool of hit points, so the Durable feat can go a really long way to keep your hit points high throughout the day.
Grappler^PHB: With the Barbarian's typically fantastic Strength, grappling can be an excellent choice.
Great Weapon Master^PHB: Barbarians are all about two-handed weapons, and Great Weapon Master offers some great options. Berserker Barbarians will find the extra attack benefit useful in fights with numerous weak enemies, allowing them to reserve their Frenzy for fights with large single enemies.
Heavily Armored^PHB: Rage doesn't function while you're wearing heavy armor.
Heavy Armor Master^PHB: Rage doesn't function while you're wearing heavy armor.
Inspiring Leader^PHB: This is generally better for more charismatic characters like Bards or Paladins, but temporary hit points are great for Barbarians. If you're building to utilize Frightful Presence, this might be worthy of consideration.
Mage Slayer^PHB: Only useful in games which feature an abnormally large number of spellcasters.
Martial Adept^PHB: One superiority die means that you might get to use your maneuvers two or three times a day at most. Feats should be more consistently useful.
Medium Armor Master^PHB: You won't be doing much stealth unless you went for Wolf Totem and have other stealthy people in your party, and the potential bonus to AC isn't enough to justify this feat on its own.
Mobile^PHB: You already get a speed boost, and Eagle totem will provide similar benefits.
Mounted Combat^PHB: Fighting while mounted can be a great option for Barbarians, and you have plenty of hit points to absorb any attacks which might target your mount.
Polearm Master^PHB: The Barbarian has very few options which require you to be within 5 ft. of a target. The base class offers Retaliation, and the Totem Warrior has a couple options (Totem Spirit (Wolf) and Totemic Attunement (Bear)), but if you're fine not relying on those options most of the time Polearm Master can be tempting. The bonus attack provided by the feat is especially interesting since you can get the damage of a two-handed weapon while still getting as many attacks as though you were using two-weapon fighting. However, there are numerous Barbarian abilities which allow you to make extra attacks as a bonus action which are already built into the class so you may find that the bonus polearm attack frequently goes unused. The ability to make an attack when something enters your reach is nice, but considering barbarians usually handle threats by charging them first you'll likely find that this benefit also rarely applies.
Resilient^PHB: Dexterity might be a good option, but certainly not before you have hit your maximum in Strength and possibly Constitution.
Savage Attacker^PHB: This is a bad feat. The largest damage die (d12), yields an average of 2 extra damage per turn. The absolute best case scenario is a half-orc berserker with Brutal Critical critting with a greataxe, but even then it's still only around 4.45 extra damage at the absolute most, and it's still limited to once per turn.
Sentinel^PHB: This is fantastic for Defender builds, and works very nicely with the Bear totem.
Shield Master^PHB: The best part of this is probably the ability to shove enemies (possibly shoving them prone) as a bonus action. Wolf totem provides a similar benefit.
Skilled^PHB: Helpful if your party has large skill gaps, but Barbarians aren't very good at skills, so your utility is severely limited.
Skulker^PHB: Even if you are in a sneaky party, you should be leaping from hiding to murder things.
Tavern Brawler^PHB: If you want to go for Grappler, this feat complements it nicely.
Tough^PHB: You need too many ability increases to make room for this feat. Instead, boost your Constitution.

Weapons

Handaxe: Your go-to option for two-weapon fighting.
Javelin: A great disposable ranged option when you're too far away to move into melee in one turn.
Greataxe: Brutal Critical means that a bigger damage die is better for you.
Greatsword: More reliable damage than the Greataxe, but not as useful with Brutal Critical.
Maul: Basically a blunt greatsword.

Armor

Multiclassing

Fighter: The Fighter's Fighting Style ability is decent if you go for two-weapon fighting, but Two-Weapon Fighting is hard since Barbarians already have several options which allow them to attack as a bonus action, allowing them to match TWF number of attacks while using a two-handed weapon. 2nd level brings Action Surge, which is fantastic on any character. At 3rd level consider the Champion archetype to pick up Improved Critical, which will double how often you get to use Brutal Critical.
Monk: Unarmored Defense abilities don't stack. You use whichever you got first, according to the official FAQ.
Rogue: A dip into Rogue for Expertise in Athletics will go a long way if you plan to use Shove or Grapple, but without the Fighter's big number of attacks Shove isn't always a great option. Cunning Action is not helpful for a Barbarian and conflicts with the numerous abilities which allow Barbarians to make attacks as a bonus action, so don't dip past first level.
Wizard: Barbarians have almost exactly opposite abilities to Wizards, so there isn't a lot of room for compatibility.

Example Build - Half-Orc Barbarian (Berserker)

Oh look, someone's using a greataxe!

This is a "Staple Build". This build is simple, and relies on options from the SRD and the Basic Rules wherever possible. If you need a functional build with nothing fancy or complicated, this is a great place to start.

This is a very simple build. Barbarians have very few decision points, and the biggest tactical decision they require in an encounter is whether or not to rage. Berserker adds the additional choice of potentially entering a Frenzy, but even that shouldn't be especially stressful.

Abilities

We'll mostly use the example ability scores described above, but we'll switch the Strength and Constitution so that we can get 16 in both after the Half-orc's racial ability score increases.

	Base	Increased
Str	14	16
Dex	14	14
Con	15	16
Int	8	8
Wis	10	10
Cha	10	10

Race

Half-Orc. Savage Attacks works great with greataxes, and I can't think of a weapon that says "barbarian" more than a greataxe. It also stacks with Brutal Critical, so you get to roll big piles of d12's at high levels.

Skills and Tools

Half-orcs get Intimidation for free, so we'll pick up Nature and Perception.

Background

Soldier. Of the limited number of options in the basic rules, Soldier is one of the best options for us. Since we already get Intimidation proficiency, we can replace the redundant proficiency with something else. We'll keep Athletics, and you can use the replacement proficiency to get Survival.

Folk Hero works equally well in terms of skills, and you can use your class skill proficiencies to get Animal Handling and Survival to turn both into open skill proficiency slots if you want something not on the Barbarian skill list.

Levels

Level	Feat(s) and Features	Notes and Tactics
1	Rage Unarmored Defense	For your starting gear, take a greataxe, two handaxes, and the explorer's pack and javelins. You don't start with armor, but with 14 Dex and 16 Con Unarmored Defense gives you 15 AC. You might buy yourself a shield, but that will mean putting down your greataxe, and you've got 15 hit points for a reason, and Rage will give you damage resistance. At this level you can only rage twice per day, but at first level adventuring days tend to be short because characters are so fragile, so you should be able to rage in most encounters.
2	Reckless Attack Danger Sense	Reckless Attack is a great ability, but obviously it comes with risks. At this level I recommend only using it in fights against powerful single foes so you're not taking repeated hits from groups of weak enemies, and even then consider raging at the same time to offset the additional damage you will inevitably take. Danger Sense is helpful for mitigating damage from AOE effects which will typically deal damage types not resisted by Rage. At this point you may have enough gold for a suit of Scale Mail, which will net you +1 AC, but after that start saving gold until you can get Half Plate.
3	Primal Path: Path of the Berserker Frenzy	Our first subclass ability is Frenzy. It's basically just better Rage, but you suffer a level of exhaustion when your rage ends. You don't want to go past two levels of exhaustion, and now that you have three rages per day that's a possibility. The combination of Frenzy and Reckless Attack is the reason greataxes are appealing for the Barbarian, so when you need to deal a bunch of damage in a hurry you can Rage, Frenzy, and use Reckless Attack to deal a whole bunch of damage in a hurry.
4	Ability Score Improvement (Strength 16 -> 18)	More Strength means more attack and more damage.
5	Extra Attack Fast Movement	5th level is an important milestone in 5e. Martial classes get Extra Attack, which roughly doubles your damage output. 5th level also requires proportionately more encounters worth of experience before you gain another level than any other level, so you're going to spend a lot of time at 5th level. Between Frenzy's extra attack and Extra Attack, you get three attacks with Advantage for a total of 6 d20 rolls, giving your probability of more than 26% to roll at least one natural 20, and every time you crit you're dealing 3d12+Str damage, which feels really satisfying.
6	Mindless Rage	Attacking a barbarian mentally is the easiest way to shut them down, so Mindless Rage is a significant defensive buff.
7	Feral Instinct	Going first feels great. It's usually not very important for barbarians because you don't need to cast a spell to alter the layout of an encounter or something, but it's still really nice.
8	Ability Score Improvement (Strength 18 -> 20)	20 Strength means that you're as strong as you'll be until you reach 20th level or find a really nice magic item.
9	Brutal Critical (1 die) Rage Damage +3	Adding another d12 roughly 25% of the time means that you're dealing something like 1.5 extra damage per turn. On average that's not much, but it feels very satisfying to roll 4d12 on a critical hit.
10	Intimidating Presence	Intimidating Presence is rarely useful because it eats your entire action. You could still Frenzy and attack as a bonus action, but I think the most likely use case for this is to begin a Rage solely for the purpose of chasing someone around and screaming at them.
11	Relentless Rage
12	Ability Score Improvement (Constitution 16 -> 18)	A Constitution increase means that your Unarmored Defense AC rises to 16, so Half Plate is still better. But you get a bunch of extra hit points, which is great.
13	Brutal Critical (2 dice)	Each greataxe hit die added by Brutal Critical adds roughly 1.5 extra damage per round on average. Between Savage Attacks and Brutal Critical, you're now rolling 4d12+Str on a critical, which feals really awesome.
14	Retaliation	Finally a good reason not to get as much AC as possible, Retaliation means that taking damage increases your damage output. Of course, but this level an AC of 17 is not safe by any stretch of the imagination, so don't go dumping your armor to try to trigger this. You won't need to.
15	Persistent Rage Rage Damage +4	Since you're a Berserker, ending a rage can carry a bigger consequence than it does for other barbarians, and effects that prevent you from acting like paralysis can force your race to end early.
16	Ability Score Improvement (Constitution 18 -> 20)	Your Unarmored Defense now matches the AC provided by half plate. Drop the armor so you're no longer suffering Disadvantage on Dexterity (Stealth) checks and wearing 40 lbs. of clothing. Of course, if you have magic armor that changes the math.
17	Brutal Critical (3 dice)	Another critical hit die, another 1.5 average damage per round. You're up to 5d12 on a critical hit now, which is pretty great,.
18	Indomitable Might	Once in a while you need to grapple, lift something, break something, etc. and by this level you already have 20 Strength, so your minimum result is 20. That's easily enough to pass normal ability check DCs, but you may lose grapple checks on very rare occasion,
19	Ability Score Improvement (Dexterity 14 -> 16)	A bump in Dexterity doesn't do much for you, but at the very least you get better initiative and +1 AC. If you don't want to increase Dexterity, this extra ability score improvement is clear indication that you have room to consider a feat.
20	Primal Champion	+2 to hit, +2 damage, minimum of 24 on all Strength checks, and +40 hit points on top of what you got just for gaining a level.