Creating a whole other class that would be similar to another with one or two added features is pointless and that's where this concept should do the job.
Whenever you'd check the NPC's class, it's Sub-class would listed right below the main one.
A few examples:
- Cops
-
Chief Officer/Warden -> More or less a boosted version of a regular cop, they will be able to call for backup and have better weaponry, but killing them should be very rewarding.
(Warden is supposed to be the Chief of prison guards) -
CQC Expert -> Often increased strength or proper traits (Kneecapper etc.). Prefers direct combat to shooting.
-
Sharpshooter -> Special cop with great aim; they will often act as snipers during hostage situations.
- Zombies
- Bloater -> Upon death, its corpse explodes into a cloud of poisonous gas
- Spitter -> Can use Zombie Phlegm
- Brute -> Particularly strong. Possesses Bulky, Knockback King, Bullet Sponge + and Tank-Like traits
- Werewolves
- Pack Leader -> Can howl for backup. As if one werewolf didn't mean business.
- Inverted Cycle -> Becomes human at night and werewolf at day.
- Tracker -> Has a great sense of smell, harder to lose during pursuits.
- Cannibals
Chef - Fights w/ a knife. Main ability: Can turn corpses into effectively healing meals; pretty much each cannibal feast makes cannibals look like they never entered a battle.
The examples may not pull through, but I hope they showcase this idea well.