Monsters refers to the many antagonistic creatures the player will encounter throughout the game.

Most monsters (with few exceptions) will damage Isaac by either touching him or shooting him with projectiles. Less frequently, monsters will spawn additional, lesser monsters, spread creep, or attempt to affect the player's movement. Along with the more common variety of monsters, champion versions can be found lurking about. These monsters are often like their common counterparts, but have a color tint or size change and drop basic pickups on death. There are also champion versions of most bosses.

There are 197 monsters in total. 39 of them were added in Afterbirth (Ultra Greed Coins counted) and 20 were added in Afterbirth † (12 were added in Booster Packs).

Monster List

Champions

Some monsters can spawn as a Champion which deviates in coloration and size from its more common form. The champion's coloration denotes which peculiar behaviors and traits it will exhibit. Champions will generally drop a pickup (coinciding with the color of the champion) when killed on normal difficulty. However, in hard mode, fewer champions will drop pickups on death. All champions will deal contact damage, regardless of what monster they are (e.g. a common Mulligan will not deal contact damage, but champion versions will). Most champions inflict full heart damage regardless of chapter and have double the health of a normal monster. The likelihood of champions appearing is increased by unlocking the Everything Is Terrible! achievement, by carrying the Purple Heart trinket, by picking up the Champion Belt item, or by playing in hard mode. Champions are generally regarded as more dangerous than common monsters.

The identifying scheme for champion qualities is as follows:

Champion Types

ID	Appearance	Effect	Drop
0	Red	×2.5 amount of HP.	Heart
1	Yellow	Increased movement and shot speed.	Little Battery
2	Green	Leaves green creep as it walks.	Pill
3	Orange	Attacks cause you to drop coins (like Greed or a Hanger).	Coin
4	Dark Blue	None.	3 Blue Flies
5	Dark Green	Explodes when killed.	Bomb
6	Solid White	Invincible until all other enemies are killed.	Eternal Heart
7	Gray	Has 2/3 health, but deals double damage.	Key
8	Transparent White	Tears become spectral tears, and it can move past environmental obstacles (such as pits) that it otherwise couldn't when forced.	Golden Chest
9	Black (with slight green tint)	Fades in and out of visibility, like a Null.	Red Chest
10	Pink	Periodically shoots short-ranged blood shots, similar to Gushers.	Nothing
11	Purple	Pulls Isaac towards itself, like a Gaping Maw.	random Trinket
12	Dark Red	Collapses into a flesh pile upon death and regenerates if not finished off (like a Globin).	1+1 Free Heart
13	Light Blue	Releases blood shots in 8 directions when killed.	1/2 heart
14	Camouflage	The enemy blends into the background and briefly becomes visible when damaged.	Rune
15	Pulsing Green	Splits into two copies of itself upon death.	2 normal versions of itself
16	Pulsing Grey	Repels Isaac's shots when it pulses.	Heart
17	Light White	Has 1-2 eternal flies circling it. Spawns another fly upon death.	Attack Fly
18	Tiny	Decreased health, increased speed and increases the pitch of its voice. Smaller and more difficult to hit.	One Makes You Small pill
19	Large	Increased health, decreased speed and decreases the pitch of its voice. Larger and easier to hit. Deals two full hearts of damage.	One Makes You Larger pill
20	Pulsing Red	All other enemies in the room regenerate health rapidly while this enemy is alive.	Heart
21	Pulsating	Spawns an Attack Fly per hit.	5 Blue Flies
22	File:Crown Effect.gif Crown	Increased health. All enemies in the room that are not champions will turn into yellow champions while the crowned enemy is alive.	2 random pickups
23	Skull	Produces a Necronomicon effect upon death.	Necronomicon effect