Pathfinder - Minions
Minions, mooks, grunts, whelps, and cannon-fodder are a fantastic addition to any encounter. It is highly satisfying to throw a fireball and watch a dozen enemies collapse.
Pathfinder lacks official rules for minions. You can try to simulate minions by adding several low-level monsters to encounters, but you will probably find that the minions have trouble harming the party in any way. This effectively makes minions useless bags of hit points to be cleaned up when the real encounter is over.
Instead, I propose the Minion template. While 4e can have minions with 1 hit point, Pathfinder needs to handle problematic effects like Magic Missile. With only 1 hit point, Magic Missile would essentially be "Remove Minion". Giving them 1 hit point per hit die puts slightly higher level minions out of reach of single Magic Missiles, but still makes them sufficiently weak that they can be felled quickly.
Minion (CR +0)
Creatures with the minion template serve bigger, stronger creatures than themselves.
Rebuild Rules: Minions deal average damage (rounded down) for any successful attack they make or spells they cast which deal damage. Minions cannot score critical hits, but still automatically hit on a natural 20.
Minions have 1 hit point her hit die, plus their constitution modifier (or whatever ability modifier contributes to their hit points). Minions with the toughness feat gain 3 hit points, but do not gain additional hit points per hit die or per level. Minions are treated as having half of their actual hit dice (rounded up) for the purposes of effects related to hit dice, such as Turn Undead, Panache, Grit, or Sleep.
Minions never take damage from a missed attack or after a successful save. Any critical hit that deals damage automatically kills a minion. A minion is worth 1/4 the normal experience value of a normal monster of its type, and should be used in a group of four.
Minions never use heroic classes. They use either racial hit dice or NPC classes. Minions generally should not wield magical weapons or items, and any treasure beyond NPC gear should be shared among their group of minions.
Potential Problems With Minions
The usage of minions will, without doubt, affect the way your game is played. Area of effect spells will be more important; Cleaving Finish might be worth the feat (finally); two-weapon fighting might become more popular. These aren't necessarily bad things, but you need to be aware so that you can be prepared for them as a Game Master.
Space and movement will be more important during encounters. With all of the extra bodies, you may need to allow for more space in your encounters which involve minions. This will, again, affect the play style of the party. Archers and other ranged attackers may become more prevalent due to the additional space, and melee characters may have problems staying in close combat. Make sure to accommodate your party's needs.
Zombie Shambler CR 1/2 (minion)
NE Medium Undead
Init +0; Senses darkvision 60 ft.; Perception +0
AC 12, touch 10, flat-footed 12 (+2 natural)
hp 5 (2+3)
Fort +0, Ref +0, Will +3
DR 5/slashing; Immune undead traits
Speed 30 ft.
Melee slam +4 (7 damage)
Str 17, Dex 10, Con -, Int -, Wis 10, Cha 10
Base Atk +1; CMB +4; CMD 14
Special Qualities staggered
Hobgoblin Grunt CR 1/3 (minion)
Minion Hobgoblin warrior 1
LE Medium humanoid (goblinoid)
Init +2; Senses darkvision 60 ft.; Perception +1
AC 16, touch 12, flat-footed 14 (+3 armor, +2 Dex, +1 shield)
hp 2 (1 HD +1)
Fort +3, Ref +2, Will +0
Speed 30 ft.
Melee longsword +4 (6 damage)
Ranged longbow +3 (4 damage)
Str 15, Dex 14, Con 13, Int 9, Wis 10, Cha 8
Base Atk +1; CMB +3; CMD 17
Feats Weapon Focus (longsword)
Skills Stealth +5; Racial Modifiers +4 Stealth
Languages Common, Goblin
Environment temperate hills
Organization gang (4–9), warband (10–24), or tribe (25+ plus 50% noncombatants, 1 sergeant of 3rd level per 20 adults, 1 or 2 lieutenants of 4th or 5th level, 1 leader of 6th–8th level, 6–12 leopards, and 1–4 ogres or 1–2 trolls)
Treasure NPC Gear (studded leather armor, light steel shield, longsword, longbow with 20 arrows, other treasure)