The Bullet Kin line
The Bullet Kin is the baseline enemy of the Gungeon, and it appears in many forms: Bullet Kin, Bandana Bullet Kin, Veteran Bullet Kin, Ashen Bullet Kin, Mutant Bullet Kin, Fallen Bullet Kin, Western Bullet Kin, Pirate Bullet Kin, Knight Bullet Kin, and Red-Caped Bullet Kin. They share the same melee-contact behavior and get tougher and more numerous the deeper you go.
Flyers and swimmers
Minelet, Bullet Fish and Red Bullet Fish attack from the air or water and force you to roll vertically, not just sideways. Shroomers lob projectiles from range.
Tanks and walls
The Tanker is a heavy bullet that soaks damage and is best answered with cover and a strong gun rather than a roll-through. Blobulins and Poisbulins are soft — any dodge roll kills them in any chamber.
Mini-bosses
Chancellors (and the Old Chancellor, and the Chancellor’s Revenge) appear as scripted mini-bosses with phased patterns, distinct from the random trash in a room.
Reading a room
Before you push in, name the family. Bullet Kin you can rush and roll through; flyers you must track vertically; tanks you punish from behind cover. Watch the first volley, then commit. The bosses on each floor are a different test entirely — see the boss guide.