The Binding of Isaac - Enemies / Characters

The Binding of Isaac Main Character Index
Main Cast | Monsters (Enemies | Bosses | Final Bosses)

Enemies

The various standard monsters of the game.

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Flies

In General

Airborne Mook: Making them immune to floor hazards, and allowing them to pass over obstacles.
Big Creepy-Crawlies: Even the weakest variety of fly (that you can actually fight) is still the size of one of Isaac's eyes.
Harmless Enemy: The Skatole item will render almost all fly enemies completely harmless towards Isaac.
Heel–Face Turn: The Beelzebub transformation will transform almost all flies into passive Blue Flies and make enemies such as Boom Flies friendly.
The Goomba: Though these ones are killed by shooting at them with tears instead of jumping on their heads.

Black Fly/Attack Fly/Ring Fly/Moter/Swarm Fly/Dart Fly/Army Fly/Hush Fly

Debut: The Binding of Isaac (Black Fly, Attack Fly, Moter)
Rebirth (Ring Fly)
Afterbirth (Swarm Fly, Dart Fly, Hush Fly)
Repentance (Army Fly)

Flying enemies that slowly hover their way towards Isaac.

All in a Row: Army Flies will chase Isaac in a single-file line.
Artificial Brilliance: Dart Flies will attempt to predict Isaac's move in order to flank him.
Asteroids Monster: Moters split into two Attack Flies when killed.
Bee Afraid: Swarm Flies and Dart Flies are likely bees or wasps given their yellow color and buzzing sound.
Bulletproof Human Shield: As the Halo Of Flies and Pretty Fly powerups. The Forever Alone and Distant Admiration powerups spawn one capable of dealing good damage.
Early-Bird Cameo: If you start your Isaac experience with Afterbirth†, you may encounter Hush flies long before you fight Hush himself.
The Goomba: One of the earliest enemies to be encountered and one of the weakest.
Harmless Enemy: Black Flies cannot damage Isaac.
Mascot Mook: The black variety is featured prominently in the artwork, and easily has the most related items.
Mook Promotion: If allowed to approach a pile of poop, a black fly consumes it and turns into a Pooter.
Spectacular Spinning: Ring Flies converge to form a spinning ring which tracks you as a group. As they're destroyed, they keep up the circle with wider gaps. Hush Flies are similar except they spin in more complex shapes, such as stars.
Zerg Rush: Swarm Flies join into a clump and then rush you.

Level 2 Fly/Full Fly

https://static.tvtropes.org/pmwiki/pub/images/level_2_fly.png

Debut: Rebirth

Larger flies that move towards Isaac in a more erratic pattern.

Elite Mooks: As the name suggests, they are standard Flies, but larger and stronger.
Kaizo Trap: Full Flies release six bullets on death.

Willo/Level 2 Willo

https://static.tvtropes.org/pmwiki/pub/images/willo_9.png

Debut: Repentance

Fire-wreathed flies that orbit around Isaac at a fixed distance and fire shots at him.

Elite Mooks: Level 2 Willos will orbit around other enemies until their host is killed, at which point they will attempt to orbit around Isaac like their weaker counterparts.
Will-o'-the-Wisp: What they're based on, fitting with Downpour's ghost theme.
Wreathed in Flames: Willos are flies on fire.

Pooter/Super Pooter/Tainted Pooter

https://static.tvtropes.org/pmwiki/pub/images/pooter_8.png

Debut: The Binding of Isaac (Pooter)
Wrath of the Lamb (Super Pooter)
Repentence (Tainted Pooter)

Flies that fire blood bullets at Isaac.

Elite Mook: Tainted Pooters are encountered during the Ascent and shoot out four large bullets that ricochet and split into two small bullets when hitting a wall or obstacle.
High-Pressure Blood: One of the first enemies you'll see that can fire bullets of blood.
Mook: Not any more dangerous than the normal flies.
Retcon: The Fat Fly was renamed "Super Pooter" in Afterbirth†.
Underground Monkey: Super Pooters shoot out two shots in a V-pattern.

Bulb/Bloodfly

https://static.tvtropes.org/pmwiki/pub/images/bulb.png

Debut: Repentance

Flies that move in extremely erratic patterns. Bulbs steal charges from your active item on contact, while Bloodflies deal damage.

Bandit Mook: Bulb flies will steal charges from your active item on touch. They're actually harmless otherwise, but can still be extremely annoying.
Confusion Fu: They move extremely erratically, which makes them hard to avoid. Fine with the harmless Bulbs, not so fine when you're facing Bloodflies.
Harmless Enemy: If Isaac has no or an uncharged active item, Bulbs will simply hover around the area. Averted with Bloodfly, who will actively pursue Isaac and can damage him.

Fly Bomb/Eternal Fly Bomb

https://static.tvtropes.org/pmwiki/pub/images/fly_bomb.png

Debut: Repentance

Small flying bombs that turn into regular tiny bombs when killed.

Action Bomb: They're bombs with wings. They drop to the ground as a tiny live bomb on death.
Invincible Minor Minion: Like their Eternal Fly counterpart, Eternal Fly Bombs cannot be damaged until the Boom Fly they orbit is killed, at which they will turn into live bombs.
Unique Enemy: Eternal Fly Bombs are only spawned by The Horny Boys.

Boom Fly/Red Boom Fly/Drowned Boom Fly/Dragonfly/Bone Fly/Sick Boom Fly/Tainted Boom Fly

https://static.tvtropes.org/pmwiki/pub/images/boom_fly.png

Debut: The Binding of Isaac (Boom Fly, Red Boom Fly)
Afterbirth (Drowned Boom Fly)
Repentance (Dragonfly, Bone Fly, Sick Boom Fly, Tainted Boom Fly)

Flies that move around diagonally and explode when killed.

Action Bomb: With the exception of the Red Boom Fly, Dragonfly and Bone Fly, they explode when killed.
All Your Powers Combined: Drowned Boom Flies will explode like a regular Boom Fly and also send out bullets like a Red Boom Fly.
Deadly Gas: Sick Boom Flies leaving poisonous gas wherever they go and release a cloud of it on death.
Dem Bones: Bone Flies are skeletal flies that fire a bone towards Isaac and shoot out three bones when killed.
Disaster Dominoes: An efficient way to clear a Boom Fly room is to kill one of them while they're all flying in a cluster. Doesn't work with Red Boom Flies, which shoot bullets in 6 directions on death instead of exploding.
Elite Mooks: Tainted Boom Flies are a much stronger version of Boom Flies encountered during the Ascent. When killed, they send out explosions in the cardinal directions across the entire room.
Mook Maker: Drowned Boom Flies can sometimes spawn a Drowned Charger when killed.
Playing with Fire: On death, Dragonflies will release waves of fire in 4 directions. The directions they hit depends on the Dragonfly's appearance: if their eyes are normal, the fire goes in the cardinal directions, and if they have "x" eyes, the fire will be launched diagonally.

Sucker/Spit/Ink/Soul Sucker/Mama Fly/Tainted Sucker

https://static.tvtropes.org/pmwiki/pub/images/sucker_2.png

Debut: The Binding of Isaac (Sucker)
Wrath of the Lamb (Spit)
Afterbirth† (Soul Sucker)
Repentance (Ink, Mama Fly, Tainted Sucker)

Flies that hover towards Isaac and release bullets when killed.

Action Bomb: Spits release an explosive Ipecac shot on death.
Disaster Dominoes: In a room with several Spits, killing one while standing in the right direction will often cause a chain reaction of vomit bombs that kill the rest of them. The same goes for Soul Suckers, which will frequently kill every other Soul Sucker in the room.
Elite Mooks: Tainted Suckers are a much stronger version of Suckers encountered during the Ascent. On death, they release six large bullets with each splitting into six smaller bullets.
Helpful Mook: A Soul Sucker's laser can damage and kill any enemy in the room with it, making them effective ways of clearing out rooms.
High-Pressure Blood: Soul Suckers release four Brimstone lasers upon death.
Mook Maker: Mama Flies will spawn Pustules that will eventually turn into Bloodflies. On death, they release Small Maggots.
Oil Slick: Inks leave a pile of black creep when killed.
Taking You with Me: They release hard-to-dodge ranged attacks for Suckers, Inks and Tainted Suckers, vomit bombs for Spits, and Brimstone lasers for Soul Suckers when killed.

Eternal Fly

Debut: Wrath of the Lamb

An invincible fly that will orbit around corn poop or other monsters.

Invincible Minor Minion: Until the monster or poop they orbit is destroyed, at least.
Meaningful Name: As mentioned above, the Eternal Fly is, well, eternal, until the poop or monster they orbit is destroyed, turning it into an Attack Fly.
Orbiting Particle Shield: Effectively a living version of this, as it orbits monsters or poops until they're destroyed, and then they'll turn into Red Flies.

Humanoid

Gaper/Frowning Gaper/Flaming Gaper/Cyclopia/Deep Gaper/Blurb/Rotten Gaper/Dead Isaac/Twitchy/Blue Gaper/Greed Gaper

https://static.tvtropes.org/pmwiki/pub/images/gaper_91.png

Debut: The Binding of Isaac (Gaper, Frowning Gaper)
Afterbirth (Flaming Gaper, Cyclopia, Greed Gaper, Blue Gaper)
Repentance (Deep Gaper, Blurb, Rotten Gaper, Twitchy, Dead Isaac)

Enemies that walk towards Isaac to deal contact damage.

Ambushing Enemy: Deep Gapers wait under the water and only attack after every other enemy is dead.
Composite Character: Twitchy alternates between acting like a Gaper and acting like a Trite.
Creepy Child: Gapers; They look much like your player character, but with Tears of Blood and a creepy smile.
Cyclops: Cyclopia, which move slower than Gapers but can fire blood tears.
Elite Mooks: Frowning Gapers to Gapers.
Everything's Deader with Zombies: Rotten Gapers are the zombie version of Gapers in the Corpse.
Eye Scream: Gapers have empty eye sockets filled with blood. The Cyclopia has only one eye in the middle of its head bleeding Tears of Blood.
Infernal Retaliation: Flaming Gapers move faster than normal. However, normal Gapers can't become Flaming Gapers by touching fire.
Meaningful Name: Cyclopia is named after a birth defect in which a fetus' eyes will fail to separate and be fused together.
Mook Maker: One Rotten Gaper variant spits up Small Maggots over time.
Losing Your Head: All Gaper varieties can become Pacers or Gushers when killed.
Our Zombies Are Different: The Gapers within Mom's Womb become undead when Isaac kills her heart early in Mausoleum/Gehenna, gaining new varieties in her Corpse in the process.
Spider People: Twitchies are Gapers with a Trite for a head.
Tears of Blood: Gapers have them on their faces. Cyclopias weaponize them in the form of creep and bullets.
Unique Enemy:
- In Afterbirth, Blue and Greed Gapers only spawn as part of the Hush and Ultra Greed fights respectively. Averted in Afterbirth†, since Greed Gapers can now spawn in item rooms and Blue Gapers can very rarely appear as regular enemies. As of Repentance Greed Gapers were replaced with Bulbs in item rooms, meaning they only spawn in Greed Mode or in one specific Super Secret Room, putting them back in this territory.
- Dead Isaacs only spawn as part of Mother's boss fight, and only during one attack in her first phase.
Zombie Puke Attack: Blurbs start with a mouth full of water, which they spit at Isaac before becoming effectively a normal Gaper.

Pacer/Gusher/Black Globin's Body

https://static.tvtropes.org/pmwiki/pub/images/pacer_71.png

Debut: The Binding of Isaac (Pacer, Gusher)
Afterbirth (Black Globin's Body)

Headless Gapers that wander around the room aimlessly.

Elite Mooks: Gushers to Pacers. Black Globin's Bodies are even more elite, spawning only in Sheol and shooting spiders instead of bullets.
High-Pressure Blood: Gushers shoot out a fountain of blood from their necks, but only the occasional blood shot can actually deal damage.
Losing Your Head: Gapers or Black Globins who have lost their heads.
Overdrawn at the Blood Bank: Gushers, as the name implies, have a constant stream of blood flowing from their necks.

Gurgle/Splasher/Crackle

https://static.tvtropes.org/pmwiki/pub/images/gurgle_8.png

Debut: Wrath of the Lamb (Gurgle)
Rebirth (Splasher)
Repentance (Crackle)

Gapers that fire explosive Ipecac shots.

Immune to Bullets: They cannot be damaged by explosive shots from other enemies.
Losing Your Head: Starting from Rebirth, Gurgles have a chance to become Splashers when killed.
Playing with Fire: Crackles launch fireballs instead of explosives.
Super Spit: They hack up explosive Ipecac shots rather than the usual damaging blood.

Wraith/Null

https://static.tvtropes.org/pmwiki/pub/images/null_6.png

Debut: Rebirth (Null)
Repentance (Wraith)

Gapers that become periodically invisible when chasing Isaac.

Invisible Monsters:
- Nulls fade in and out of sight while pursuing Isaac.
- Wraiths are permanently invisible, but still leave reflections in the water. In the mirror world, they're instead fully visible and leave no reflections.
Nightmare Face: Wraiths look a little unsettling in Downpour. They upgrade to a straight-up scary face in Dross, looking totally black colored with yellow-tinted eyes and mouth.
See the Invisible: The occasional lightning strike in Downpour will render Wraiths briefly visible.

Horf/Psychic Horf/Sub Horf/Necro/Tainted Sub Horf

https://static.tvtropes.org/pmwiki/pub/images/horf_7.png

Debut: The Binding of Isaac (Horf)
Rebirth (Psychic Horf)
Repentance (Sub Horf, Necro, Tainted Sub Horf)

Floating heads that shoot blood bullets at Isaac when near them.

Ambushing Enemy: Downplayed by Sub Horfs. They appear identical to regular Horfs while not in the Downpour or Dross, potentially taking you by surprise when they suddenly spin when shot.
Counter-Attack: Sub Horfs will spin and fire tears as they take damage.
Dem Bones: Necro is a Horf skull that summons bones and flings them towards Isaac in any direction.
Elite Mook: Tainted Sub Horfs are stronger Sub Horfs encountered during the Ascent that fire much faster when hit.
Eye Scream: Horf eye sockets are filled with blood.
Pinball Projectile: Inverted. Sub Horfs are the ones that bounce around like pinballs when struck, firing a shot of their own in a random direction.
Third Eye: Psychic Horfs possess one, which allows them to fire homing shots.
Tears of Blood: Both have them, but only regular Horfs fire them.
Wreathed in Flames: Necros are surrounded in a purple flame.

Hopper/Flaming Hopper/Leaper/Eggy/Sticky Leaper/Tainted Hopper

https://static.tvtropes.org/pmwiki/pub/images/hopper_8.png

Debut: Binding of Isaac (Hopper, Flaming Hopper)
Wrath of the Lamb (Leaper)
Repentance (Eggy, Sticky Leaper, Tainted Hopper)

Headless enemies that jump around the room.

Acrofatic: Sticky Leapers are noticeably more bloated than regular Leapers but are still able to perform their jump attack.
Bullet Hell: Leapers shoot bullets in all four cardinal directions when they jump. If five end up in a room, be prepared to dodge.
Elite Mooks: Tainted Hoppers are stronger Hoppers encountered during the Ascent. They jump around much quicker and fire a ring of shots containing 4, then 6, then 8, then finally 12 bullets.
Infernal Retaliation: Flaming Hoppers move twice as fast, jump twice as far, and inflict more damage.
Mook Maker: Eggy will release a ton of Swarm Spiders when killed.
Mook Promotion: A Hopper that touches fire becomes a Flaming Hopper.
Oil Slick: Sticky Leapers will shoot out several tar shots and leave a pile of black creep wherever they land.
Violation of Common Sense: An enemy example. Not only does every other enemy (or character, even) take damage themselves from fire, but Isaac's main combat strategy is attacking enemies with water. Despite that, they seem to have double health.

Maw/Red Maw/Psychic Maw

https://static.tvtropes.org/pmwiki/pub/images/maw_16.png

Debut: The Binding of Isaac (Maw, Red Maw)
Wrath of the Lamb (Psychic Maw)

Emaciated Horfs that will slowly drift towards Isaac while firing shots at him.

Elite Mooks: Maws themselves are basically Horfs, only with the ability to move, which eliminates the tactic of staying just outside of their range and shooting.
Eye Scream: Psychic Maws have their eyes sewn shut.
Kaizo Trap: Red Maws will fire four blood shots when killed.
Knockback: Red Maws get knocked away farther when hit, offsetting their speed in terms of how easily you can keep them at bay (especially if you have a high rate of fire), but making it difficult to line up multiple shots against them.
Mouth Stitched Shut: Red Maws and Psychic Maws have their lips stitched, which means they can't shoot. To compensate, the Red Maws can chase you pretty fast.
Orbiting Particle Shield: Psychich Maws will have an Eternal Fly circling them.
Tears of Blood: The Psychic Maw has this. The other Maws may have this, but it looks more like their eyes may have exploded out of their sockets instead.
Third Eye: Psychic Maws possess one, which allows them to fire homing shots in lieu of their stitched mouth.

Mr. Maw/Mr. Red Maw/Mr. Mine/Swinger

https://static.tvtropes.org/pmwiki/pub/images/mr_maw_1.png

Debut: Wrath of the Lamb (Mr. Maw)
Rebirth (Swinger)
Afterbirth† (Mr. Red Maw, Mr. Mine)

Maws attached to a body with a fleshy neck, which allows them to fling their heads towards Isaac.

Aquatic Mook: Mr. Mines only appear on the Flooded Caves. Makes sense, considering they're meant to be sentient sea mines.
Asteroids Monster: Depending on whether you kill it by shooting it in the head or "body", Mr. Maw will spawn a Maw or Gusher, Mr. Red Maw a Red Maw or Gusher, and Swinger a Maw or Globin.
Detachment Combat: Mr. (Red) Maws and Mr. Mines will swing their heads out at you when you get close. Swingers are perpetually swinging, as their name suggests. Mr. (Red) Maw can also voluntarily separate into a (Red) Maw and a Gusher.
Epic Flail: Their heads can be swung around like these.
Kaizo Trap: Mr. Mine doesn't have a body to break apart into, but fires six shots in all directions upon death.

Skinny/Crispy/Rotty

https://static.tvtropes.org/pmwiki/pub/images/skinny_3.png

Debut: Rebirth (Skinny, Rotty)
Afterbirth† (Crispy)

Gapers with melted faces that leave creep when walking towards Isaac.

Asteroids Monster: The Rotty downplays this, as it has a chance to spawn a few flies upon death.
Body Horror: It has a more deformed appearance than most humanoid enemies. Crispies have it worse, as they're on fire, so their flesh is melting even more.
Critical Status Buff: Crispies gain more movement speed the lower their health is. Given that they're on fire, they also slowly power themselves up.
Incendiary Exponent: Crispies are on fire and eventually burn to death. They speed up as their health drains.
Punny Name: "Skinny" not only refers to the folds of skin hanging off their faces but also sets them up as a Fat and Skinny duo with the Fatty.
Stripped to the Bone: Non-fatal variant; killing a Rotty will sometimes cause it to become a Bony.

Danny/Coal Boy

https://static.tvtropes.org/pmwiki/pub/images/danny_3.png

Debut: Repentance

Enemies that spit out rocks towards Isaac.

Dishing Out Dirt: Danny spits out rocks, which can sometimes contain Rock Spiders.
Playing with Fire: Coal Boy will spit out hot coals, which can sometimes contain Coal Spiders.

Bony/Black Bony/Revenant/Quad Revenant/Big Bony/Holy Bony

https://static.tvtropes.org/pmwiki/pub/images/bony_8.png

Debut: Rebirth (Bony)
Afterbirth (Black Bony)
Repentance (Revenant, Quad Revenant, Big Bony, Holy Bony)

Walking skeletons that throw a bone towards Isaac if they spot him.

Action Bomb: Black Bonies explode on death.
Ballistic Bone: Their main form of attack is tossing bones with good accuracy whenever Isaac gets in their line of sight.
Breath Weapon: Revenants attack by breathing a stream of purple fire toward Isaac. Quad Revenants do it from four mouths at once.
Dem Bones: A walking skeleton that throws bones at Isaac.
Elite Mook: Big Bonies are Fatty skeletons that throw big bones that will bounce around the room for a bit before breaking.
Palette Swap: Revenants in Gehenna have a black appearance and in inverted cross on their forehead.
Playing with Fire: Holy Bonies throw bones wreathed in a blue flame that leave small blue flames where it lands.
Stock Femur Bone: The bones these enemies throw are femur bones.

Clickety Clack

Debut: Repentance

Skeletal enemies that collapse in piles of bones when killed before reassembling themselves, only dying for real if every Clickety Clack is down at the same time.

Dem Bones: They're skeletal variants of Globins.
Expy: You know the Dry Bones from Super Mario Bros.? The Clickety Clacks are the Isaac answer to them.
Pulling Themselves Together: They collapse into a pile of bones on death, but will quickly reassemble themselves. They only die for good if every Clickety Clack in the room is dead at once.

Maze Roamer

Debut: Repentance

Mummy skeletons that spawn in pairs and attack Isaac by firing an eyeball from their eye socket.

Cyclops: Each have one eye due to the other being covered in rags. The exposed eye is opposite on the two pairs.
Dem Bones: With their appearance, the only indicator that they're skeletons is that they collapse into bones when killed.
Differently Dressed Duplicates: They always spawn in pairs, and you can tell them apart because one is bloody and the other is clean.
Eye Scream: They attack by launching eyeballs out of their empty sockets.
Mummy: A bandage-wrapped skeleton.
Turns Red: Maze Roamers start moving and attacking more quickly when their partner is killed.

Fatty/Flaming Fatty/Pale Fatty/Bubbles/Bloaty/Fat Sack/Blubber/Half Sack/Conjoined Fatty/Quakey/Vis Fatty/Peeping Fatty/Stoney/Cross Stoney/Blue Conjoined Fatty/Shady/Gutted Fatty

https://static.tvtropes.org/pmwiki/pub/images/fatty_2.png

Debut: Rebirth (Fatty, Pale Fatty, Fat Sack, Blubber, Half Sack)
Afterbirth (Flaming Fatty, Conjoined Fatty, Blue Conjoined Fatty)
Afterbirth† (Stoney, Cross Stoney)
Repentance (Bubbles, Bloaty, Quakey, Vis Fatty, Peeping Fatty, Shady, Gutted Fatty)

Fat enemies that slowly walk towards Isaac, occasionally farting to knock him back.

Acrofatic: While they're normally slow and bumbling, Fat Sacks have an attack where they jump high in the air and slam down. Averted with Stonies, who get out-of-breath after a while of chasing after Isaac.
Amazing Technicolor Population: Blue Conjoined Fatties, a rare enemy with a rather outlandish skin tone. Averted in Repentance, as described below.
Art Evolution: In Repentance, Blue Conjoined Fatties were redesigned to resemble Hush.
Body Horror: Gutted Fatties were apparently split open from groin to jaw, letting their insides spill free.
Boss in Mook Clothing: Shadies may have only 80 HP, but they're one of the few normal enemies with armor, making them take significantly more punishment. In addition, their attacks are loud and very dangerous.
Dishing Out Dirt: Quakies attack by slamming on the ground hard, firing 8 rock shots and causing several rocks to fall from the ceiling.
Dead Weight: Fat Sacks are fat zombies. Played more literally with Gutted Fatties, who are more blatantly zombified versions.
Elite Mook: Shadies have armor and attack by either firing shots that split and spread outwards when hitting a wall or obstacle, or by jumping and unleashing a line of explosions in the cardinal directions that span the entire room.
Everything's Deader with Zombies: Gutted Fatties are the zombie version of Fatties residing in the Corpse.
Eye Scream:
- Peeping Fatties have their eyes dangling out of their heads, which can block shots.
- Gutted Fatties lose their eyes as they take damage, which bounce around the room Peep-style until the Fatty is killed.
Fat Bastard: It's all in their names.
Fetus Terrible: Vis Fatties have a Fetal Demon attached to them, which will lunge at Isaac if he gets close.
Gasshole: Fatties can fart to push things away. Pale Fatties shoot blood when they do this.
Half The Man They Used To Be: Half Sacks are the lower, still mobile bottom part of Blubbers.
High-Pressure Blood: When a Vis Fatty's Fetal Demon is killed, they will fire a Brimstone laser from their stomach and fly around the room backwards diagonally.
Infernal Retaliation: Flaming Fatties are faster than normal and can leave a flame obstacle when killed.
Invincible Minor Minion: Stonies behave just like Fatties but only die when every other enemy is killed.
Kaizo Trap: Bubbles are bloated Fatties that unleash a geyser of water bullets when killed, which will rain down on Isaac.
Kevlard: They're decently durable, and that probably comes from their immense fat.
Living Shadow: Shadies seem to be living shadow versions of Fatties, similar to Dark Judas.
Losing Your Head: Blubbers are Pale Fatties or Fat Sacks that have lost their heads.
Mook Maker: Gutted Fatties fling their Festering Guts out occasionally, which slide around and spawn Chargers of their own. Gutted Fatties also pop their eyes out as their health gets lower.
Multiple Head Case: Conjoined Fatties have two heads. "Killing" it only destroys one head, reducing it to a regular Fatty.
Nerf: Stonies were eventually changed to catch their breath every so often instead of chasing players without pause, as their release version made rooms too hard to clear.
Nightmare Face: The Fat Sack's face, with the empty eye sockets and Tears of Blood. Not to mention its perpetual frown. Gutted Fatties also have a fairly gnarly expression on their faces, their eyes bugging out of their sockets while they're lacking a jaw.
Poisonous Person: Bloaties will cough up green creep along with several bullets.
Red and Black and Evil All Over: Shadies, in a similar vein to Dark Judas.
Turns Red: When a Fetal Demon's Vis Fatty is killed, they will chase after Isaac similar to Suture.
Unique Enemy: Cross Stonies only appear in Challenge #33, Aprils Fool, as a replacement for regular Stonies.

Mulligan/Mulligoon/Mulliboom/Nest/Hive/Drowned Hive/Prey/Mullighoul/Gas Dwarf/Bouncer/Leper/Swarmer/Holy Mulligan/Tainted Mulligan

https://static.tvtropes.org/pmwiki/pub/images/mulligan_34.png

Debut: The Binding of Isaac (Mulligan, Mulligoon, Hive)
Wrath of the Lamb (Mulliboom, Swarmer)
Rebirth (Nest)
Afterbirth (Drowned Hive)
Afterbirth† (Leper)
Repentance (Prey, Mullighoul, Gas Dwarf, Bouncer, Holy Mulligan, Tainted Mulligan)

Enemies with deformed heads that run away from Isaac when approached.

Action Bomb:
- Normal Mulligans puff up and explode into flies if they survive long enough and get cornered.
- Mulligoons replace the flies with a 4-way shot plus a troll bomb.
- Mullibooms come with bombs implanted in them and will charge and blow up on you.
- The Swarmer spawns a Bomb Fly upon death.
- Gas Dwarves cough up farts, and launch an Ipecac projectile on death that can blow their fart clouds up.
Asteroids Monster: As Lepers takes damage, small pieces of Leper Flesh will break off until the Leper turns into a Gusher.
Body Horror:
- The tumour-headed Mulligan grows more decayed as the flies inside it transform it into the Hive. From there, the Hive becomes a Swarmer, a rotten head filled with flies.
- Leper heads are mostly comprised of Fistula-like flesh barely held together by gristle. As pieces continue to break off, the Leper's slowly gets reduced piece-by-piece until it loses its head entirely and becomes a Gusher.
- The Bouncer's entire body is one giant tumour, which it can somehow inflate.
- Instead of coughing up flies, Holy Mulligans birth Angelic Babies out of their eyes. At least they look happy about it?
- Like all the Tainted enemies, Tainted Mulligans look like they're in constant pain, with their tumors severely overgrown.
Elite Mook: Tainted Mulligans are stronger Mulligans encountered during the Ascent. They cough up entire swarms of Ring Flies and explode into a hive of flies on death.
Ghastly Ghost: Mullighouls are ghostly Mulligans that cough up Willos.
Incurable Cough of Death: Has a very distinctive-sounding one when it spits up flies to attack you.
Mook Maker: Hives, Nests, Drowned Hives, and Prey occasionally cough up Attack Flies, Spiders, Drowned Charges, and Small Leeches respectively before spitting them at you, and Swarmers constantly spawn small flies as well as Pooters and Super Pooters when damaged. All varieties, other than the Mulliboom, Mulligoon, Gas Dwarf, and Bouncer, spawn various enemies when killed.
- Holy Mulligans will shoot out Small Angelic Babies from its eye and spawn one to two Embryos when killed.
Retcon: Gas Dwarves used to be named Fartigans prior to one of the Repentance updates.
Shows Damage: The ring of flies around a Swamer will deplete as its health is lowered.
Taking You with Me: Unlike his cousins, the Mulliboom (the one with a bomb stuck in his head) will rush straight at you and try to suicide-bomb you. Bouncers are similar, but instead function by bum-rushing you and forcing you to dodge the shots they explode into on death.

Blaster

Debut: Repentance

Cannon-headed enemies that fire Bomb Flies at Isaac.

Hoist by His Own Petard: They're extremely tanky, but will die instantly if they're hit by an explosion. Luckily, their only method of attack is spawning exploding flies.
Mook Maker: They lob Fly Bombs.
Palette Swap: They have a dustier appearance in Ashpit.
Rock Monster: They appears to be made out of stone.

Globin/Gazing Globin/Dank Globin/Black Globin/Cursed Globin/Cohort

https://static.tvtropes.org/pmwiki/pub/images/globin_2.png

Debut: The Binding of Isaac (Globin, Gazing Globin)
Afterbirth (Dank Globin, Black Globin)
Repentance (Cursed Globin, Cohort)

Enemies that collapse into a pile of goo when killed, reforming themselves after a short time.

Artificial Brilliance: They will move coordinately to trap you. Especially problematic in rooms with obstacles.
Asteroids Monster:
- The Cursed Globin. Coupled with their regenerative abilities, one Cursed Globin can swiftly multiply into a dozen. Thankfully, each split reduces the spawned Globins' HP, so they won't be too tanky.
- Cohorts are basically big Globins resembling Monstro, and split into four Globins upon death.
Boss in Mook Clothing: The Cohort is essentially a Globin version of Monstro. It has similarly high HP and splits into piles of Globin flesh on death.
Eyeless Face: Every Globin variant that isn't a Gazing or Cursed Globin has no eyes in their sockets.
Elite Mooks: The versions with one eye are faster and have more health. Their meat pile also slides away diagonally a short distance to avoid being hit. Dank Globins spawn a spider and a puddle of tar whenever they collapse.
Pulling Themselves Together: When killed, they will become a pile of goo and then recover. Luckily, they will take less to kill next time. Cursed Globins weaponize this, splitting into more and more piles of goo as they die until they eventually get worn out.
Punny Name: With "goblin" and "hemoglobin".
Self-Duplication: Every time a Cursed Globin dies, it spawns two puddles of goo instead of one. To compensate, they have lower health than than other Globin variants and can "only" split about fifteen times.
Why Won't You Die?: Unless you finish off the pile of goo, this will happen. The main problem is attacking the goo while several others are chasing you.

Knight/Selfless Knight/Floating Knight/Loose Knight/Brainless Knight/Black Knight/Bone Knight

https://static.tvtropes.org/pmwiki/pub/images/knight_7.png

Debut: The Binding of Isaac (Knight, Selfless Knight)
Rebirth (Floating Knight)
Afterbirth (Bone Knight)
Repentance (Loose Knight, Brainless Knight, Black Knight)

Enemies that will charge towards Isaac and can only be damaged via their exposed brains.

Airborne Mook: Floating Knights are flying Knight heads, ignoring pits and barriers.
Attack Its Weak Point: The front of them is solid bone or petrified flesh. The only way to actually damage it is to hit it in the back of its head, the exposed brain.
Attack Reflector: Any tears blocked by Black Knights will be reflected right back at the player.
Bloody Murder: Bone Knights trail damaging creep behind them, making it more difficult to target the exposed brain.
Composite Character: Brainless Knights are connected to a Pon that must be killed to destroy them, basically making them a Mask + Heart variant.
Elite Mooks: Selfless Knights are faster compared to regular Knights and have a crying Isaac face instead of a brain on their back.
Playing with Fire: Black Knights will launch waves of fire in cardinal directions when hitting a wall.
Shield-Bearing Mook: As customary, the solution is to flank it where its shield can't protect it.

Vis/Double Vis/Chubber/Scarred Double Vis/Vis Versa/Evis

https://static.tvtropes.org/pmwiki/pub/images/vis_69.png

Debut: The Binding of Isaac (Vis)
Wrath of the Lamb (Double Vis, Chubber)
Afterbirth (Scarred Double Vis)
Repentance (Vis Versa, Evis)

Headless enemies that fire a brimstone laser from their stomachs.

Body Horror: They look like headless humans, only with a gaping hole on their chests that shoots Brimstone lasers in one or multiple directions.
Bloody Murder: Fires what appears to be blood in a wide beam across the room it's in.
Combat Tentacles: Instead of shooting a laser, Evises latch a tentacle on to Isaac. It doesn't deal damage, but slowly drags Isaac towards them.
The Computer Is a Cheating Bastard: The Chubber is a variation that fires Lil' Chubby instead of a beam. Their Lil' Chubby can go through rocks and deal damage on the return trip, but yours can't do either.
Elite Mooks: Double Vis fires Brimstone both in front of and behind it, and Scarred Double Vis shoots in all four cardinal directions.
Eyes Do Not Belong There: Vis Versa has an eyeball inside the hole in its stomach (which itself is upgraded to a Belly Mouth). It's used to fire a homing Brimstone beam.
Helpful Mook: Their lasers can damage other non-Vis enemies, which make them handy for clearing rooms.
High-Pressure Blood: They shoot huge streams of blood that pass through all obstacles. In fact, they're probably the first enemy you'll see that can use Brimstone.
Meaningful Name: Evis' name is short for evisceration, which is how they attack Isaac.
Palette Swap: Vis spawned by The Cage have a gray coloration, and Vis Versa in Gehenna will have a black coloration.
Vagina Dentata: Are the normal Vis not Freudian enough for you? Vis Versa's hole is filled with teeth.

Faceless/Fanatic/Tainted Faceless

https://static.tvtropes.org/pmwiki/pub/images/faceless_3.png

Debut: Repentance

Enemies with half of their head ripped off that chase Isaac and fire blood shots in all directions.

Composite Character: Tainted Facelesses are a Faceless crossed with a Fatty.
Facial Horror: They're Gapers with the top half of their face ripped off. It's not so bad on the regular Faceless since they're Made of Bologna, but the Tainted version has a much more violent rip and still has their bottom jaw visible.
Losing Your Head: Or at least, losing half of it. It doesn't stop them from chasing Isaac. They also have a chance to fully lose their head and turn into a Pacer or Gusher on death.
Unique Enemy: Fanatics only appear as part of the Heretic fight, being the cultists that summon him that are "rewarded" with being turned into headless servants.

Bishop

Debut: Repentance

Enemies that create a shield around all other enemies in the room with them.

Counter-Attack: They will occasionally fire shots in cardinal directions after taking damage. It's pretty easy to dodge, but a step up from Antibirth where they were totally defenseless.
Mook Medic: Their main purpose is protecting other enemies. Every time another enemy would take damage (except other Bishops), the Bishop will prevent it.
Redemption Demotion: If you make a Bishop friendly, it will shield you but takes all the damage it blocks instead of outright preventing it.
Shoot the Medic First: Unless you focus down the Bishop first, you won't have much luck trying to damage enemies in the room.
Sinister Minister: As their name suggests.
Stationary Enemy: They cannot move from their spot.

Whipper/Snapper/Flagellant

https://static.tvtropes.org/pmwiki/pub/images/whipper.png

Debut: Repentance

Monsters that attack Isaac with fleshy whips.

Adaptational Name Change: In Antibirth, Flagellants were called Lunatics.
The Berserker: If Flagellants spot Isaac, they begin wildly whipping in front of them while running forwards.
Combat Tentacles: They're not just holding whips, the whips are part of their arms. Whippers and Flagellants swipe in an arc in front of them, while Snappers launch their whip straight across the entire room.
Eyes Do Not Belong There: Snappers have an eyeball inside of their open mouths, despite still having regular eyeholes on their hoods.
Facial Horror: Flagellants have their jaws ripped off.
Punny Name: Whippers and Snappers combine to make the word whippersnapper.
A Taste of the Lash: Flagellants are cover in whip wounds. Whether they were being punished (they are found in Sheol) or it's self-inflicted isn't clear.
Whip of Dominance: The Whipper and Snapper variants in Gehenna are wearing gimp suits, giving their whips a much more disturbing connotation.

Baby/Wrinkly Baby/Angelic Baby/Unborn

https://static.tvtropes.org/pmwiki/pub/images/baby_70.png

Debut: The Binding of Isaac (Baby)
Wrath of the Lamb (Angelic Baby)
Repentance (Wrinkly Baby, Unborn)

Undead babies that will fire shots at Isaac and occasionally teleport around the room.

Body Horror: Flying, blood-covered fetuses.
- The Wrinkly Baby, being a heavily decayed version of one, is this up to eleven. Its voice is even lower-pitched to match its appearance.
Dem Bones: Wrinkly Babies look like skeletal babies.
Elite Mooks: Angelic Babies shoot a three-way spread shot instead of one bullet. Wrinkly Babies charge at Isaac first before firing the triple shot.
Fetus Terrible: Think of the familiar babies you can get, only shrieking and bloody. Unborn play this more straight, being actual fetuses that float towards Isaac in a circular fashion.
Light Is Not Good: The friendly and less harmful looking Angelic Baby is actually more dangerous due to it having a spread attack.
Teleport Spam: Will frequently disappear into the nether before reappearing elsewhere a moment later.
Weaponized Teleportation: Unborns will occasionally teleport to Isaac's other side in an attempt to flank him.

Dople/Evil Twin

https://static.tvtropes.org/pmwiki/pub/images/dople_1.png

Debut: The Binding of Isaac

Enemies that mirror Isaac's movements and attacks.

Doppelgänger: The Evil Knockoff variety.
Elite Mooks: The Evil Twin. Instead of looking like a meat puppet, it looks like a demon that can: fly, shoot a triple-shot and do more damage. Thankfully, its bullets travel slower and it has a fixed fire rate, giving you time to dodge and shoot.
Enemy Without: They mirror the player's movements, including shooting, but most rooms come with a mechanism with which to destroy them. There are also bombs, and praying that whipped shots will work.
Flaying Alive: Dople has no skin.
Foreshadowing: The appearance of these foreshadows the nature of Isaac the boss.
Mirror Match: They can perfectly mimic Isaac's movements and attack at the same time, though they cannot replicate certain tear properties.

Keeper/Hanger

https://static.tvtropes.org/pmwiki/pub/images/keeper_29.png

Debut: Wrath of the Lamb

Reanimated shopkeepers that shoot bullets which will cause Isaac to drop coins if they hit him.

Adorable Evil Minions: The Keepers to Ultra Greed, as he will spawn them during his boss battle. The idea of small head creatures flopping clumsily around a boss arena doesn't sound too threatening, does it?
Airborne Mook: Hangers dangle from the ceiling, letting them pass over pits and obstacles.
Bandit Mook: When they hit you, you lose three cents. Only two of those cents fall onto the ground to be picked up again.
Orbiting Particle Shield: Each Hanger has an Eternal Fly defending it.

Mole/Fred/Tainted Mole

https://static.tvtropes.org/pmwiki/pub/images/mole_3.png

Debut: Wrath of the Lamb (Fred)
Repentance (Mole, Tainted Mole)

Enemies that burrow underground, popping up to fire a shot before jumping into the ground again.

Body Horror: Fred is based on a baby with Harlequin-type ichthyosis.
By the Lights of Their Eyes: A Mole's visible eyes can be seen in Curse of Darkness or the blackout rooms in the Mines.
Call a Smeerp a "Rabbit": Moles don't really look like moles, rather they're little humanoids.
Elite Mook: Tainted Moles are stronger Moles encountered during the Ascent. They cause rockwaves when they travel and fire three shots rapidly after popping up.
Mad Bomber: Fred will shoot an explosive Ipecac shot at Isaac.
Toilet Humor: Tained Moles leave a pile of poop from where they jumped.
Whack-a-Monster: They pop up in random areas of the room and attack either by firing an explosive shot or shooting a spray of bullets while diving through the air, before going underground and repeating the process. Moles prefer to dig towards Isaac first before they pop up to attack.
Wormsign: Moles (but not Freds) leave one of these while travelling underground.

Buttlicker/Butt Slicker

https://static.tvtropes.org/pmwiki/pub/images/butt_licker.png

Debut: Wrath of the Lamb (Buttlicker)
Repentance (Butt Slicker)

Enemies that travel in a conga line/cluster, wandering randomly.

Asteroids Monster: The segments split and act independently after one of them dies.
Oil Slick: Butt Slickers leave a pile of black creep when killed.
Toilet Humor: Besides constantly tossing each other's salads, they'll eat poop. Doesn't get much more toilet-humorous than that.

Goat/Black Goat

https://static.tvtropes.org/pmwiki/pub/images/goat_8.png

Debut: Repentance

Weak goat-headed humans that attack in huge swarms and try to charge at Isaac.

Dash Attack: Goats will charge at Isaac if on either side of him.
Elite Mooks: The rarer Black Goats will fire 4-way Brimstone lasers occasionally, similarly to The Fallen and Krampus.
Gruesome Goat: Herds of goat monsters that roam in Gehenna.
Wave-Motion Gun: Black Goats occasionally launch a quad-firing Brimstone beam attack.
Zerg Rush: Goats are fairly weak, but attack in huge swarms.

Homunculus/Begotten

https://static.tvtropes.org/pmwiki/pub/images/homunculus_2.png

Debut: Rebirth

Enemies that are chained to the wall, but will eventually break free and begin chasing Isaac.

Body Horror: Homunculus's warped facial features.
Blackout Basement: A Begotten will darken the room if it breaks free.
Breaking the Bonds: They become significantly more dangerous when they break their chains and can pursue you.
Expy: They start out trying to get at the player while chained but can break free and chase them, not unlike the Chain Chomp.
Invisible Monsters: Begotten becomes this once it breaks loose, similar to the Null. Fortunately, it also has the same Invisibility Flicker.
Nightmare Face: Begottens have really frightening-looking facial exprssions.

Level 2 Gaper/Level 2 Horf/Level 2 Gusher

https://static.tvtropes.org/pmwiki/pub/images/level_2_gaper.png

Debut: Repentance

A much more powerful Gaper, that splits into a Horf and Gusher on death.

Asteroids Monster: Killing a Level 2 Gaper just knocks its head off, letting its body run around while the head keeps attacking.
Body Horror: They blend in with the environment given how they all look like rotting, shambling monsters with some parts missing.
Elite Mooks: They're upgraded versions of their respective basic enemy types, found only in the Corpse and Ascent.
Everything's Deader with Zombies: Alongside the Gutted Fatty and Rotten Gapers, they're the only explicitly zombified enemies in the game.
Losing Your Head: Taking enough damage makes a Level 2 Gaper split into a Level 2 Horf (spits Small Maggots at Isaac) and a Level 2 Gusher (runs around spawning Small Maggots)
Our Zombies Are Different: They only became undead when Isaac killed Mom in the Mausoleum/Gehenna with the assembled Knife. They got stronger in the process.

Worms and Grubs

Maggot/Small Leech/Small Maggot

https://static.tvtropes.org/pmwiki/pub/images/maggot_7.png

Debut: The Binding of Isaac (Maggot)
Repentance (Small Leech, Small Maggot)

Worms that wriggle around and can deal contact damage.

The Goomba: Has no attacks, and just wanders around the room randomly. Small Leeches downplay this, as while they're still fragile, they at least actually try to squirm towards Isaac for Collision Damage.

Charger/Drowned Charger/Dank Charger/Carrion Princess

https://static.tvtropes.org/pmwiki/pub/images/charger_3.png

Debut: The Binding of Isaac (Charger)
Afterbirth (Drowned Charger)
Afterbirth† (Dank Charger)
Repentance (Carrion Princess)

Grubs that will charge until they hit a wall if Isaac lines up with them.

Attack Its Weak Point: Just like Carrion Queen, you can only hurt Carrion Princesses by shooting them in the butt.
Deadly Lunge: If they spot Isaac, they will open their mouths wide and speed towards him... exactly like Chub does. Dank Chargers also bounce around the room afterwards, but have to catch their breath before they can charge again.
Dem Bones: Carrion Princesses are skeletal variants of Chargers.
High-Pressure Blood: What sets Drowned Chargers apart is that they burst into shots of blood when killed.
Oil Slick: Like a lot of Dank Depths enemies, Dank Chargers leave slippery oil everywhere they crawl.

Level 2 Charger/Elleech

https://static.tvtropes.org/pmwiki/pub/images/level_2_charger_5.png

Debut: Repentance

Bigger, tougher Chargers that will curve towards Isaac when chasing him.

Elite Mooks: Bigger, tougher versions of Chargers. Elleeches can even charge through walls to get you.
Odd Name Out: Elleech is the only Ascent enemy to not feature Tainted in its name.
Punny Name: Elleech is an obtuse play on "elite" and "leech" (despite the fact that they aren't actually leech variants).

Spitty/Conjoined Spitty/Tainted Spitty

https://static.tvtropes.org/pmwiki/pub/images/spitty_9.png

Debut: The Binding of Isaac (Spitty, Conjoined Spitty)
Repentance (Tainted Spitty)

Maggots that occasionally fire projectiles from their mouths.

Elite Mook: Tainted Spitties are stronger Spitties encountered during the Ascent. They fire a line of bullets, constantly shoot bullets from their rear, and release a ring of bullets when killed.
Multiple Head Case: The conjoined version has a head on both ends, letting it spit blood in both directions simultaneously.
Super Spit: Their method of attacking, as their name implies.

Leech/Kamikaze Leech/Holy Leech/Adult Leech

https://static.tvtropes.org/pmwiki/pub/images/leech_03.png

Debut: Wrath of the Lamb (Leech, Kamikaze Leech, Holy Leech)
Repentance (Adult Leech)

Flying enemies that quickly rush towards Isaac if they spot him.

Action Bomb: Kamikaze and Holy Leeches will explode on death.
Deadly Lunge: Their main attack is to charge at Isaac at high speed. Adult Leeches release a ring of 12 bullets when colliding with a wall.
Death from Above: Adult Leeches will periodically burrow underground and attempt to crash into Isaac from above.
Elite Mooks: Kamikaze to regular Leeches, and Holy to Kamikaze Leeches.
Giant Mook: Adult Leeches are this to all the other Leeches.
Orbiting Particle Shield: The Holy variant has an Eternal Fly guarding it.

Grub

Debut: Rebirth

A huge segmented worm that splits into various maggots, spitties, and chargers on death.

Asteroids Monster: Each of its segments becomes a lesser variety of maggot on death.
Boss in Mook Clothing: Grubs are basically a stronger version of Larry Jr. In some boss fights against the latter, one of them is replaced with a Grub.
Deadly Lunge: Will lunge at Isaac if it spots him.

Round Worm/Nightcrawler/Tube Worm/Fire Worm/Roundy/Ulcer/Tainted Round Worm/Tainted Tube Worm

https://static.tvtropes.org/pmwiki/pub/images/round_worm_8.png

Debut: The Binding of Isaac (Round Worm)
Rebirth (Nightcrawler)
Afterbith (Roundy, Ulcer)
Afterbirth† (Tube Worm)
Repentance (Fire Worm, Tainted Round Worm, Tainted Tube Worm)

Worms that pop out of the ground to fire at Isaac then emerge somewhere else in the room.

Bullet Hell: The Tube Worm attacks by spraying a massive barrage of tears in the air, which fall near Isaac.
Cyclops: Night Crawlers are one-eyed Round Worms that fire bullets that spiral outwards.
Dishing Out Dirt: Roundies unleash a small rockwave wherever it emerges from.
Elite Mook: Tainted Round Worms and Tainted Tube Worms are stronger variants that can be encountered during the Ascent. Tainted Round Worms will pop out multiple segments of its body, each of which will fire a bullet at Isaac. Tainted Tube Worms spit out 4 explosive Ipecac shots at Isaac.
Fast Tunnelling: All of them can submerge and re-emerge anywhere in the room quickly.
Helpful Mook: A Roundy's rockwave can not only clear out other enemies in the room, but can also destroy tinted rocks and reveal secret and super secret rooms.
Living Lava: Fire Worms appear to be made out of magma.
Mad Bomber: Roundies will fire an explosive Ipecac shot at Isaac.
Mook Maker: Ulcers will spawn Dart Flies if left alone.
Playing with Fire: Fire Worms will shoot fire at Isaac.

Para-Bite/Scarred Para-Bite/Cod Worm

https://static.tvtropes.org/pmwiki/pub/images/parabite7.png

Debut: The Binding of Isaac (Para-Bite)
Rebirth (Cod Worm)
Afterbirth (Scarred Para-Bite)

Worms that chase Isaac and can instantly tunnel to another spot in the room.

Counter-Attack: Shooting at a Cod Worm while it is hiding in its shell will cause it to retaliate with a burst of tears.
Losing Your Head: Scarred Para-Bites are Para-Bites with their heads ripped off.
Shield-Bearing Mook: Cod Worms are entrenched in hard shells which they can retreat into at will.
Zerg Rush: Para-Bites will bum-rush you endlessly, only briefly backing away to repeat the process.

Needle/Pasty

https://static.tvtropes.org/pmwiki/pub/images/needle_79.png

Debut: Repentance

Worms that leap out of the ground to hit Isaac, with no prior warning that they're in the room.

Ambushing Enemy: They hide underground until Isaac gets near them. Unlike Mom's Hands, there's no warning that a Needle is in the room.
Elite Mooks: Fittingly, Pasties are based on The Frail and fire shots in ordinal directions when jumping.
Punny Name: Needles are tiny versions of Pin.
Worm Sign: They leave a small one when emerging, which is your only warning that a Needle is about to pounce.

Fistuloid

Debut: Afterbirth†

A grub wrapped in fistula flesh that launches at Isaac on death.

Body Horror: As the name implies, it's a tiny Fistula.
Kaizo Trap: Fires a maggot towards Isaac on death.

Spiders

Spider/Strider/Swarm Spider/Big Spider

https://static.tvtropes.org/pmwiki/pub/images/spider_7.png

Debut: Wrath of the Lamb (Spider, Big Spider)
Repentance (Strider, Swarm Spider)

Enemies that alternate between standing still and very quickly moving in a random direction.

Alien Blood: Inverted. The spiders in this game have red blood despite spiders in real life actually having pale blue blood.
Asteroids Monster: Big Spiders split into two after death.
Walk on Water: Striders are well, water striders. They behave exactly the same as regular spiders, but they can cross over gaps on the Downpour and Dross since they're filled with water.
Zerg Rush: Swarm Spiders have the lowest health of any enemy in the game. However, they come in packs of twenty or more.

Level 2 Spider/Ticking Spider/Migraine

https://static.tvtropes.org/pmwiki/pub/images/level2spider_9.png

Debut: Rebirth (Level 2 Spider, Ticking Spider)
Repentance (Migraine)

Stronger spiders that can also leap short distances.

Action Bomb: Ticking Spiders explode when killed. Migraines drop three live troll bombs.
Elite Mooks: Like the Level 2 Fly family, they are improved versions of standard spiders.
Having a Blast: Killing them tends to result in explosions.
Taking You with Me: It can happen if you don't get away from them before they blow up on death.

Baby Long Legs/Small Baby Long Legs/Crazy Long Legs/Small Crazy Long Legs

https://static.tvtropes.org/pmwiki/pub/images/babylonglegs_7.png

Debut: Rebirth

Spiders that move very quickly and erratically, stopping occasionally to fire shots/spawn enemies.

Mook Maker: Baby Long Legs make Spiders, while their Small counterparts create Sacks.
Weaponized Offspring: Both versions of the Baby Long Legs spawn spiders to attack Isaac with, though they don't seem too happy about it.

Rock Spider/Tinted Rock Spider/Coal Spider

https://static.tvtropes.org/pmwiki/pub/images/rock_spider.png

Debut: Repentance

Spiders covered in a rocky shell that become normal spiders once it's destroyed.

Infernal Retaliation: If a Rock Spider touches fire, it turns into a Coal Spider.
Kaizo Trap: Coal Spiders leave hot coals where they die, which can still hurt Isaac if he touches them.
Piñata Enemy: Like regular Tinted Rocks, Tinted Rock Spiders drop Soul Hearts on death. However, they only spawn when blowing up a tinted rock in the Mines or Ashpit in place of any Soul Hearts you would've gotten.

Wall Creep/Blind Creep/Rage Creep/The Thing/Soi Creep/Tainted Soi Creep

Wall Creep/Blind Creep/Rage Creep/The Thing/Soi Creep/Tainted Soy Creep

https://static.tvtropes.org/pmwiki/pub/images/wallcreep_6.png

Debut: Rebirth (Wall Creep, Blind Creep, Rage Creep)
Afterbirth† (The Thing)
Repentance (Soi Creep, Tainted Soi Creep)

Spiders that move alongside a wall, attempting to line up with Isaac.

Eye Scream: The Blind Creep, Rage Creep, and The Thing seem to be missing their eyes.
High-Pressure Blood: The Rage Creep fires a Brimstone laser when Isaac moves in front of it while The Thing creates a blood creep.
More Dakka: Soi Creeps fire a continuous stream of shots, similar to the effect of Soy Milk.
Shout-Out: The Thing is a reference to The Thing (1982), particularly drawing on the scene where The Thing turns into a spider-like monster with a human head.
Wall Crawl: They can only move by crawling along the walls.

Trite/Ragling/Rag Man's Ragling/Blister

https://static.tvtropes.org/pmwiki/pub/images/trite_2.png

Debut: Wrath of the Lamb (Trite, Ragling)
Afterbirth (Rag Man's Ragling)
Afterbirth† (Blister)

Spiders seemingly made out of a human head, which can leap long distances to hit Isaac.

Deadly Lunge: They normally hop around the room randomly, but if the player gets close, they will actively leap at the player; notably, when attacking, they can leap much farther than normal.
Giant Spider: They're about the size of Isaac's head.
Shout-Out: A Trite is a head-on four legs, with an eye-like mouth in the center. In other words, a tektite. It's also a shout out to the Doom³ enemy of the same name, which also has an upside down head.
Tears of Blood: The Trite.

Poop

In General

One-Hit Kill: Using Flush! will instantly kill any of them instantly, without turning them into "regular" poop.
Talking Poo: Actually, it's more like yelling poo.
Toilet Humor: Regular poop lying everywhere not good enough for you? Now you can fight the poop!

Dip/Corn/Brownie Corn/Big Corn/Drip

https://static.tvtropes.org/pmwiki/pub/images/dip_8.png

Debut: Rebirth (Dip)
Afterbirth (Corn, Brownie Corn)
Repentance (Big Corn, Drip)

Extremely low-health enemies that move short distances in random directions.

Cute Slime Mook: For whatever your definition of "slime" is. They're definitely filling this role, as the cutest creatures in the game.
Kaizo Trap: Big Corns will shoot their big corn at you on death.
One-Hit-Point Wonder: Corns and Brownie Corns are the weakest enemies in the game, dying in only one hit just with regular tear damage. Dips are only slightly tougher, taking two hits.
Stealth Pun: Dips. (Which are made out of...)

Squirt/Dank Squirt/Splurt/Hardy

https://static.tvtropes.org/pmwiki/pub/images/squirt_01.png

Debut: Rebirth (Squirt)
Afterbirth (Dank Squirt)
Repentance (Splurt, Hardy)

Bigger poop monsters that charge at Isaac and split into Dips on death.

Asteroids Monster: Squirts split into two Dips when killed. Dank Squirts split into two Clots instead.
Dash Attack: They all can do this, to varying degrees:
- Normal Squirts charge once and leave it at that.
- Dank Squirts leave slowing creep as they charge.
- Splurts make an extra dash after the first one.
- Hardies charge for longer distances, and if they crash into a solid surface they fracture slightly and spray rock projectiles outward.
Dishing Out Dirt: If Hardies collide with the wall, they'll fire rock projectiles outward.
Rule of Three: Hardies can only use their charge attack three times; after the third time, they automatically crumble to leave behind a Dip.

Dinga

Debut: Rebirth

Giant poop monsters that stomp the ground for a projectile attack and break into Squirts on death.

Asteroids Monster: They break into two Squirts when killed, which likewise break into Dips/Clots.
Ground Pound: They can jump up and stomp the ground to launch projectiles in a ring around them.
Mook Maker: Their stomps will spawn dips.

Dump/Dump Head

https://static.tvtropes.org/pmwiki/pub/images/dump_3.png

Debut: Repentance

Enemies that slowly move towards Isaac. On death, the Dump's head will separate and bounce around the room while its body continues to fire at Isaac.

Losing Your Head: After taking enough damage, the Dump's head will pop off and bounce around the room. Once it comes to a stop, it'll slowly follow Isaac.
The Turret Master: After splitting, the body will temporarily remain in place as a turret.

Poot Mine

Debut: Repentance

Gasbags that bounce around and fart when hit, exploding and igniting their farts when they die.

Fartillery: Every time they take damage, they'll leave a cloud of gas and propel themselves in a random direction. The farts are harmless by themselves, but watch out when you kill them...
Farts on Fire: On death, they explode, igniting every gas cloud they left behind.

Fly Trap

Debut: Repentance

A poopy humanoid surrounded by a ring of flies that it can replenish.

Mook Maker: It spits out attack flies.
Orbiting Particle Shield: It has a ring of three flies protecting it, which block shots and pursue you once the Fly Trap dies.

Henry

Debut: Repentance

An exceedingly rare enemy that spawns in one single room in the Dross, and is totally harmless.

Anti-Frustration Features: He is rare and it is very hard to kill him before he dies himself. To make up for these, he is not a part of the Bestiary, so the player does not have to grind runs to search Dross and find him.
Cat Scare: He is designed to look like he might be a tougher enemy or even a "miniboss," with his size and special "arena"-type room. But all he really does is flush himself and the player becomes free to go.
Damage-Sponge Boss: Henry has about 80HP, something that only endgame enemies would normally have. This is to make sure that he can flush himself down the drain as you normally wouldn't be able to deal enough damage to kill him.
Easter Egg: The encounter with him is more of a secret, he's mostly there to treat the player with the sight of a unique enemy that kills itself shortly after it spawns.
Harmless Enemy: Henry does not directly attack the player and flushes himself down shortly after he spawns, dying. It is still possible to take collision damage from him, but that requires flight and actively trying to be hurt by him. He does not even have a death drawing on Isaac's Last Will when killed by him.
Toilet Humor: He is a giant pillar of poop, and the only thing he does is flush himself down.
Unique Enemy: Only appears in one room with a low weight in Dross, and said room cannot be generated by a Red Key^note. He is the rarest "enemy" in the entire game, and he is almost completely harmless.

Other

Clot/I. Blob/Ministro

https://static.tvtropes.org/pmwiki/pub/images/clot_8.png

Debut: The Binding of Isaac (Clot)
Wrath of the Lamb (I. Blob)
Afterbirth† (Ministro)

Blobs that hop around and rapidly fire projectiles.

All Your Powers Combined: The I. Blob's projectiles, which are a combination of the Clot and Clotty.
Blob Monster: Meat blob, tar blob, and... whatever the I. Blob is made of.
Bullet Hell: They tend to shoot haphazardly, and very often, in every direction.
The Cameo: Clot is very similar to Gish.
Elite Mooks: The I. Blob variant shoots projectiles in all eight directions. Ministro forgoes directional shots and does a Monstro-type spray attack.

Clotty/Grilled Clotty/Cloggy/Mega Clotty

https://static.tvtropes.org/pmwiki/pub/images/clotty.png

Debut: The Binding of Isaac (Clotty)
Afterbirth (Mega Clotty)
Repentance (Grilled Clotty, Cloggy)

Meat monsters that rapidly fire shots in cardinal directions.

Asteroids Monster: Mega Clotty will split apart into two Clotties on death.
Cartoon Meat: They look like a living haunch of meat.
Divergent Character Evolution: Clotties, as the name implies, were original alternate versions of Clots that shot cardinally instead of ordinally. However, Afterbirth gave them a 'boss monster' with the Mega Clotty, and Repentance gave them two distinct variants. Combined with their very different appearance, they're pretty much a different monster entirely.
Infernal Retaliation: Grilled Clotties are formed when a Clotty touches fire. They shoot even more erractically.
Toilet Humor: Cloggies are Clotties made of poop. With the meat bone still stuck in them for some horrible reason.

Gyro/Grilled Gyro

https://static.tvtropes.org/pmwiki/pub/images/gyro_9.png

Debut: Repentance

Wheels of meat that roll around, trying to crash into Isaac.

Food Eats You: It's a wheel of meat that attacks Isaac.
Infernal Retaliation: Gyros will turn into Grilled Gyros on contact with fire, becoming faster and tougher.
Our Monsters Are Weird: Even by the standards of this game, a wheel of meat that rolls around while attached to a bone is pretty out there. Edmund himself pointed out how out-of-place they are (although the fact that they weren't cut implies there's some charm to them).
Rolling Attack: They roll around, attempting to charge at Isaac occasionally.

Host/Red Host/Hard Host/Walking Host/Walking Red Host/Floating Host

Host/Red Host/Walking Host/Walking Red Host

https://static.tvtropes.org/pmwiki/pub/images/host_9.png

Debut: The Binding of Isaac (Host)
Wrath of the Lamb (Red Host)
Rebirth (Walking Host, Walking Red Host)
Repentance (Hard Host, Floating Host)

Fleshy creatures that hide inside skulls. Their skulls are impervious to damage, but they must briefly expose themselves in order to fire.

Attack Its Weak Point: Only in the grey variation. To hit them, you must wait for them to expose the flesh under the skull. Moving them over spikes will also kill them.
The Cameo: From a multiplayer flash game with the same name.
Dishing Out Dirt: Hard Hosts release rock waves instead of tears.
No-Sell: Regular Hosts are protected by their skull when they aren't firing. Trying to hit them does nothing. Trying to bomb them just causes their head to flatten in a strange way.
Shield-Bearing Mook: The skulls the normal variety cover themselves with are impervious to pretty much any normal damage source.

Meatball

Debut: Afterbirth

A ball of meat that becomes a Host when destroyed.

Body Horror: It's a sentient lump of mangled meat with an exposed skull that becomes a Host when damaged enough.
High-Pressure Blood: Its main attack is to spew a veritable fountain of bloody tears.

Brain/Poison Mind/Pon/Black Globin's Head/Festering Guts/MemBrain

https://static.tvtropes.org/pmwiki/pub/images/brain_4.png

Debut: The Binding of Isaac (Brain, MemBrain)
Afterbirth (Black Globin's Head)
Afterbirth† (Poison Mind)
Repentance (Pon, Festering Guts)

Brains that leave behind trails of creep wherever they move.

Action Bomb: Post-Repentance, Poison Minds explode on death. Since they're green and floating, this makes them hostile versions of Bob's Brain.
Asteroids Monster: MemBrain splits into two Brains when killed.
Brain Monster: Of the "Just Brain" variety.
Divergent Character Evolution: In Afterbirth†, Poison Minds were green Palette Swaps of Brains that moved diagonally but were otherwise identical. Repentance reworked them into flying enemies that explode on death.
Losing Your Head: As the name implies, Black Globin's Head is the head of a Black Globin. They behave like brains. Likewise, Pons spawn when killing a Loose Knight and need to be killed to destroy the corresponding Brainless Knight.
Punny Name: Pons are named after the pons region of the brain, but also refer to the pawns in chess when paired with Knights.

Guts/Scarred Guts/Slog/Cyst/Mama Guts/Dead Meat

https://static.tvtropes.org/pmwiki/pub/images/guts_9.png

Debut: The Binding of Isaac (Guts, Mama Guts)
Afterbirth (Scarred Guts)
Repentance (Slog, Cyst, Dead Meat)

Balls of organs that roll alongside walls.

Asteroids Monster: Like the MemBrain, Mama Guts breaks apart into two Guts on death. Dead Meat breaks into two Cysts.
Body Horror: Does a rolling ball of organs sound pleasant to you?
Elite Mooks: Scarred Guts leave creep while they roll, and are slightly harder to kill. Cysts will fire at Isaac if he's nearby.
Organ Autonomy: Quite literally, they're organs that move on their own.
Rolling Attack: Guts and Scarred Guts only behavior is rolling around aimlessly on walls. Slogs are similar, but can charge at Isaac if he lines up with them.

Poky/Slide/Wall Hugger/Grudge

https://static.tvtropes.org/pmwiki/pub/images/poky_6.png

Debut: The Binding of Isaac (Poky)
Wrath of the Lamb (Slide)
Rebirth (Wall Hugger)
Repentance (Grudge)

Invincible spike enemies that damage Isaac on contact and each have different rules for when they move.

Anti-Frustration Features: Wall Huggers will have their spikes retracted for a few seconds upon entering a room, giving you time to get out of their way without taking damage from them.
Invincible Minor Minion: All varieties are immune to everything other than the Chaos Card. Pokies will die if the other enemies in the room are killed; Slides, Wall Huggers, and Grudges will not, and thus remain dangerous if you have to traverse the room again.
Spikes of Doom: Mobile blocks covered in dangerous spikes.

Spikeball/Ball and Chain/Singe's Ball

https://static.tvtropes.org/pmwiki/pub/images/spikeball.png

Debut: Repentance

Invincible spike ball traps.

Invincible Minor Minion: Like Pokies, they're obstacles and can't be killed by anything short of a Chaos Card.
Unique Enemy: Singe's Balls only appear in Singe's boss fight, and are destroyed when the fight is over.

Stone Grimace/Vomit Grimace/Cross Grimace/Triple Grimace/Gaping Maw/Broken Gaping Maw/Bomb Grimace/Quake Grimace/Constant Stone Shooter/Stone Eye/Brimstone Head

Stone Grimace/Vomit Grimace/Cross Grimace/Gaping Maw/Broken Gaping Maw/Constant Stone Shooter/Stone Eye/Brimstone Head

https://static.tvtropes.org/pmwiki/pub/images/stone_grimace_4.png

Debut: The Binding of Isaac (Stone Grimace)
Wrath of the Lamb (Vomit Grimace)
Rebirth (Gaping Maw, Broken Gaping Maw, Constant Stone Shooter, Stone Eye, Brimstone Head)
Afterbirth† (Cross Grimace)
Repentance (Triple Grimace, Bomb Grimace, Quake Grimace)

Invincible turrets that perform various attacks on Isaac.

Disaster Dominoes: Vomit Grimaces are often found together with Boom Flies, which are not immune to the vomit projectiles.
Earthquake Machine: The Quake Grimace releases rock waves in front of it.
Helpful Mook: Bomb Grimaces don't really count as enemies at all, as their only function is to give you bombs that can be picked up and thrown.
High-Pressure Blood: Brimstone Grimaces can shoot blood in a strong beam.
Invincible Minor Minion: They usually shut off after all other enemies in a room are dead, however.
Living Statue: Statue heads which fire projectiles.
Obvious Rule Patch: The Broken Gaping Maw was originally created for one room, for only one purpose; because the room used to house four standard Gaping Maws in the center, and a player character with flight and sufficiently low speed could become trapped forever in the center of their combined gravity. The Broken Gaping Maw shuts off periodically, allowing the player to escape. Booster Pack #5 made them far more ubiquitous.
Vacuum Mouth: Gaping Maws are constantly breathing in, which will suck Isaac and other things towards it.

Boil/Gut/Sack/Blue Boil/Gush/Pustule/Walking Boil/Walking Gut/Walking Sack

https://static.tvtropes.org/pmwiki/pub/images/boil_5.png

Debut: The Binding of Isaac (Boil)
Wrath of the Lamb (Gut, Sack, Walking Boil, Walking Gut)
Rebirth (Walking Sack)
Afterbirth (Blue Boil)
Afterbirth† (Gush)
Repentance (Pustule)

Immobile enemies that gain health and grow in size over time, and can attack Isaac while at their full size.

Elite Mooks: As of Wrath of the Lamb, there is the Gut, which shoots green bombs, much like Sloth. As well as mobile versions of each.
Healing Factor: The non-mobile versions slowly regenerate over time when damaged. However, they spawn with less-than-full HP and can't attack until they've reached their maximum health. Their health is directly proportional to their size.
Mook Maker: Sacks are made of spider silk, which spits out spiders. It, too, has a mobile version. Pustules grow until they either explode into a Bloodfly or are destroyed early and spawn a maggot.
Oil Slick: Gush is unique because it does no damage, it just leaves oil in a growing radius around it. It can make it hard to dodge other enemies, though.
Smashed Eggs Hatching: Pustules will spawn a fully-formed Bloodfly if left alone, but still pop out a few maggots if killed early.

One Tooth/Fat Bat

https://static.tvtropes.org/pmwiki/pub/images/onetooth.png

Debut: Rebirth (One Tooth)
Afterbirth (Fat Bat)

Flying bats that attempt to lunge at Isaac.

Artificial Brilliance: The Fat Bat actively tries to avoid your shots as it approaches you. However, it's not quite fast enough to dodge effectively.
Bat Out of Hell: Doesn't look very menacing in comparison to most examples, but it attacks all the same.
Deadly Lunge: One Tooth will dash at the player if it gets close.
Incredibly Durable Enemies: The Fat Bat's slow speed is offset by its abnormally large health pool and erratic movement, especially for an enemy that appears starting from the Caves.
Kevlard: Fat Bats are quite... well, fat. And tanky, too.

Dukie

Debut: Afterbirth

A miniature Duke of Flies that coughs up Dart Flies.

Mook Maker: Spawns Dart Flies as it bounces around the room.
Punny Name: A play on the Duke of Flies, who they resemble, and a slang word for poop.

Eye/Bloodshot Eye/Holy Eye

https://static.tvtropes.org/pmwiki/pub/images/eye_26.png

Debut: The Binding of Isaac (Eye, Bloodshot Eye)
Repentance (Holy Eye)

Immobile eyeballs that fire lasers at Isaac.

Adaptation Name Change: Eyes were renamed to Mom's Eyes in Four Souls. A weird recursive example with Holy Eyes, which debuted in Four Souls under the name Holy Mom's Eyes but had the Mom's part dropped for their video game version.
Elite Mooks: The Bloodshot Eye looks like a red (white in the original) eyeball and nothing else. It shoots Brimstone lasers instead of electrical beams.
Eye Beam: Their entire schtick. Eyes shoot Technology lasers, Bloodshot Eyes fire Brimstone, and Holy Eyes rain down Crack the Sky-style light beams.
Eye Scream: Being giant eyes, it's inevitable.
Faceless Eye: They're giant eyes that are found just lying on the ground.
High-Pressure Blood: Bloodshot Eyes fire Brimstone lasers.
Ironic Name: In the original, the Bloodshot Eye simply looked like a normal white eyeball, while the regular Eye looked bloodshot with various veins surrounding them. This was reversed in Rebirth.
Stealth Pun: Bloodshot Eye is an eye that shoots blood.

Mask + Heart/Mask II + 1/ 2 Heart

Mask + Heart/Mask II + 1/2 Heart

https://static.tvtropes.org/pmwiki/pub/images/mask_heart.png

Debut: Wrath of the Lamb (Mask + Heart)
Repentance (Mask II + 1/2 Heart)

An invulnerable mask that tries to chase Isaac and a heart that tries to flee from him.

Attack Its Weak Point: The Mask is completely immune to all damage. The Heart isn't.
Half the Man He Used to Be: 1/2 Hearts have been cut in two. You'll have to kill both to destroy their associated Mask.
Organ Autonomy: The hearts are not defenseless: they will attempt to run away from Isaac and will defend themselves with a four-way blood burst if he gets too close.
Turns Red: Once a half heart is dead, Mask II will start bleeding from its eyes and chases Isaac more aggressively.

Death's Head/Dank Death's Head/Flesh Death's Head/Redskull/Dusty Death's Head/Cursed Death's Head/Brimstone Death's Head

https://static.tvtropes.org/pmwiki/pub/images/deaths_head.png

Debut: Rebirth (Death’s Head)
Afterbirth (Dank Death’s Head, Flesh Death’s Head)
Repentance (Redskull, Dusty Death's Head, Cursed Death's Head, Brimstone Death's Head)

Flying skulls that bounce around the room. Many varieties of them are immune to damage and only die when every other enemy is cleared out.

High-Pressure Blood: Flesh Death's Heads will burst into shots of blood when they die, either from manual shooting or from the room being otherwise cleared.
Invincible Minor Mook: The standard variety keep bouncing around the room until every kill-able enemy in it is dead. They aren't immune to the Chaos Card, but why would you waste a Chaos Card on one? The Dank, Flesh, and Redskull varieties can be killed like any normal enemy; Dank Death's Heads must be destroyed to clear a room, while the other two will also automatically die if the other enemies in the room are killed.
Playing with Fire: Redskulls will periodically release waves of fire.
Supernatural Fear Inducer: Cursed Death's Heads have a fear aura around them that will prevent Isaac from shooting if he stands in it.
Taking You with Me: Flesh Death's Heads explode into 6 bullets launched in all directions when killed, either directly or by destroying all other enemies in the room.

Lil' Haunt/Candler

https://static.tvtropes.org/pmwiki/pub/images/lil_haunt.png

Debut: Rebirth (Lil' Haunt)
Repentance (Candler)

Tiny ghosts that move in circular patterns and occasionally fire shots at Isaac.

Adorable Evil Minions: They're quite cute, even though they want to kill you.
Artificial Brilliance: Lil' Haunts move in ways to try and corner Isaac, making them much more difficult to avoid compared to other enemies.
Expy: Lil' Haunts are basically the Isaac equivalent of Boos.
Playing with Fire: Candlers leave little flames behind them everywhere they go.

Wizoob/Red Ghost/Dust

https://static.tvtropes.org/pmwiki/pub/images/wizoob.png

Debut: Rebirth (Wizoob)
Afterbirth (Red Ghost)
Repentance (Dust)

Ghosts that spend most of their time invisible, only popping in to fire at Isaac.

Expy: With their attack method and name, Wizoobs are clearly based off of the original Wizrobes.
High-Pressure Blood: Red Ghosts fire a Brimstone laser attack instead of a projectile spray.
Whack-a-Monster: Wizoobs and Red Ghosts will pop up near Isaac, fire off an attack, and then disappear for an extended period of time before repeating the process. Dusts are similar, but will actively chase Isaac and disappear temporarily when taking damage.

Polty/Kineti

https://static.tvtropes.org/pmwiki/pub/images/polty.png

Debut: Repentance

Ghosts that pick up and throw objects in the room.

Chest Monster: They pop out of pots, buckets, or skulls. They can become literal chest monsters when you unlock Haunted Chests, which is a chest type that contains a Polty.
Improvised Weapon: Rocks, TNT, buckets, poop... if it's an obstacle that can be picked up, these guys will use it as a weapon.
Poltergeist: If the name didn't make it obvious, Polties are ghosts that pick things up and throw them at you.
Pstandard Psychic Pstance: Kinetis take one while pulling in objects to throw.
Psychic Powers: Kinetis don't need to fly to objects to pick them up, instead pulling them right into their hands with their minds.

Cultist/Blood Cultist

https://static.tvtropes.org/pmwiki/pub/images/cultist_58.png

Debut: Repentance

Robed ghosts that summon and revive enemies.

Animate Dead: Cultists can revive other enemies.
Black Cloak: They're all shrouded in these.
Cult: Part of one within the Mausoleum/Gehenna alongside the Goats, Whippers, and Snappers.
Elite Mooks: Despite their similar appearances, Blood Cultists have an entirely different (and very dangerous) attack method. If Isaac gets in sight of one, they'll fire a line of creep towards him. They also summon bone traps around the room that snare Isaac in place if he steps on one.
Faceless Eye: The only facial feature visible under their hoods.
Suspiciously Similar Substitute: They fill the role of Necromancers and Exorcists, enemies from Antibirth that were cut.

Imp/Baby Begotten

https://static.tvtropes.org/pmwiki/pub/images/imp_64.png

Debut: Afterbirth (Imp)
Repentance (Baby Begotten)

Demonic babies that attempt to dodge Isaac's shots and teleport around the room.

Artificial Brilliance: The only enemy in the game to make an active effort of anticipating incoming shots and dodging out of the way.
Breath Weapon: Baby Begottens fire short-ranged Brimstone beams.
Teleport Spam: Imps teleport to a random spot in the room after firing 3 shots.
Underground Monkey: A Sheol variant of Baby enemies.

Mom's Hand/Mom's Dead Hand

https://static.tvtropes.org/pmwiki/pub/images/momshand.png

Debut: Rebirth (Mom’s Hand)
Afterbirth (Mom’s Dead Hand)

Disembodied hands that hide on the ceiling, attempting to fall on Isaac and send him back to the starting room. Their presence is announced by Mom's laughter at the start of the room.

Ambushing Enemy: They hide on the ceiling of rooms, eventually diving down on Isaac.
Evil Laugh: Mom's laugh is the cue that they're in the current room.
Helping Hands: Not at all helpful to you, mind, but they still fit the trope.
Mook Bouncer: In addition to dealing damage, Mom's Hand also pulls you back to the starting room of the floor if they grab you. This can actually be helpful for a quick trip back to the starting room on a dead end, if you have the hearts to spare. Not so with the Dead variety, which simply deals damage.

Tumor/Psy Tumor/Planetoid/Poofer/Camillo Jr.

https://static.tvtropes.org/pmwiki/pub/images/tumor_4.png

Debut: Rebirth (Tumor, Psy Tumor, Camillo Jr.)
Repentance (Planetoid, Poof)

Floating tumors that rapidly fire shots in all directions as they take damage.

Bullet Hell: They shoot haphazardly in all directions at irregular intervals. Additionally, they shoot more frequently at low health, so fighting multiple Tumors can get messy very quickly.
Eye Beams: Camillo Jr. attacks with lasers rather than bullets.
High-Pressure Blood: Poofers puff up as you shoot them, and eventually explode into a huge puddle of red creep.
Mook Medic: Poofers will heal all other enemies when they die.
Shout-Out: Camillo Jrs. have their name based off of Kracko Jr. However, they look more like regular Kracko, so the Jr. is likely there to make the inspiration clearer.
Turns Red: All varieties will shoot more frequently as they take damage.

Nerve Ending/Nerve Ending II

https://static.tvtropes.org/pmwiki/pub/images/nerveending_0.png

Debut: Rebirth (Nerve Ending)
Afterbirth† (Nerve Ending II)

Immobile nerves that soak damage for other enemies and deal contact damage.

Body Horror: It's a GIANT DISEMBODIED NERVE ENDING!
Combat Tentacles: Nerve Ending II will try to swipe at you if you get too close.
Expy: The Nerve Ending II's color scheme and method of attack bear more than a passing resemblance to a Spine Crawler.
The Goomba: The Nerve Ending's only way ot dealing damage is if you run into it. Otherwise it's completely harmless. Nerve Ending II averts this by whipping at you if you get close.
Joke Character: Nerve Ending doesn't attack, it just blocks bullets. By the time you're far enough into a run to see these guys, that's already not a problem. Nerve Ending II actually does attack, though (it swats at you), which may take some players by surprise the first time they get near them. It can also replace regular Nerve Endings in room layouts, forcing you to stay on your toes.

Lump/Tar Boy

https://static.tvtropes.org/pmwiki/pub/images/lump_0.png

Debut: The Binding of Isaac (Lump)
Afterbirth† (Tar Boy)

Fleshy blobs that spend most of their time underground, only popping up extremely briefly to fire an attack.

Fast Tunnelling: They can move around "underground" very quickly.
Teleport Interdiction: Tar Boys can only pop up in spots with oil on the ground. However, they can make oil with their shots and often spawn in rooms with Gushes that can makes lots of oil for them.
Whack-a-Monster: When approached, they will fire in the player's general direction to distract them, then go underground and pop up in another part of the room.

Oob/Black Maw

https://static.tvtropes.org/pmwiki/pub/images/oob.png

Debut: Rebirth

Cameos from Super Meat Boy that Wrap Around the screen, trying to charge into Isaac.

Action Bomb: Black Maws explode when killed and can spawn Kamikaze Leeches, which also explode.
Enemy Summoner: Both are capable of spawning more enemies: Oob summons Brains, while Black Maw spawns Leeches.
Shout-Out: They are directly taken from Super Meat Boy, another Edmund McMillen game. The former was an enemy, the latter was an obstacle.

Dark Ball/Purple Ball/Visage Plasma

https://static.tvtropes.org/pmwiki/pub/images/dark_ball_3.png

Debut: Afterbirth (Dark Ball)
Afterbirth† (Purple Ball)
Repentance (Visage Plasma)

Floating balls that aggressively chase Isaac but take heavy knockback.

Homing Projectile: They veer towards Isaac, breaking away if they take damage but quickly reorienting.
Invincible Minor Minion: Purple Balls are completely indestructible, and only die when Rag Mega does.
Unique Enemy: Purple Balls are only seen in the Rag Mega fight or summoned by Cultists. Likewise, Visage Plasmas are only spawned by The Visage. Dark Balls used to be exclusive to Little Horn and occasional Greed Mode encounters, but now they can very rarely be found as regular enemies.

Portal/Lil Portal

Portal

Debut: Afterbirth† (Portal)
Repentance (Lil Portal)

Portals that spawn waves of enemies.

Foreshadowing: They are identical in appearance to the entrance to the Void, which is the manifestation of Isaac's mental breakdown.
Demoted to Extra: In Repentance, portals went from appearing on every floor to only showing up in the Void. Lil Portals also only spawn in Mausoleum/Gehenna and aren't as dangerous.
Mook Maker: Their only purpose is to spawn random enemies until destroyed.
Nerf: Shortly after release, Portals were changed to expire on their own after spawning 1-5 enemies instead of spitting out enemies indefinitely until destroyed.
Non-Standard Character Design: Those spinning vortexes are definitely not mutilated humanoids like most of the other enemies, nor bugs, nor do they even fit the "demonic" category too well. This is suggesting that they are something "outside" of the narrative Isaac made up — they represent his mind breaking down.

Mushroom

Debut: Afterbirth†

Mushrooms with faces that alternate between an ordinal and cardinal shot, and take greatly reduced damage while not firing.

Incredibly Durable Enemies: They have a very large health pool, especially for an enemy that can show up as early as the Caves. Attacking while their faces are exposed deals higher damage.
Mushroom Man: It's a mushroom with a face, though that's hardly unusual compared to some of the other enemies present.

Fissure

Debut: Repentance

Fish-like skulls that hop out of pits and bounce until they reach another, which endlessly respawn until the room is cleared.

Bouncing Battler: All they do is hop out of one pit and bounce across the ground until they fall into another. You can change their trajectory by shooting them, however.
Respawning Enemies: Fissures will endlessly respawn until either all other enemies in the room are killed or all buttons in the room are pressed.

Morningstar

Debut: Repentance

Living spikeballs that move towards Isaac, building speed. However, they stop moving whenever Isaac does and need to rebuild momentum.

Gathering Steam: They get faster and faster as you move, eventually far exceeding your possible max speed.

Mockulus

Debut: Repentance

Invulnerable eyestalks that can only move when Isaac moves, dealing contact damage.

Can't Move While Being Watched: A variant. They can only move while Isaac is moving. They generally spawn in massive numbers as part of puzzle rooms, where you need to control your movement to clear paths so you can reach buttons.
Faceless Eye: They're floating eyestalks with no other body.
Invincible Minor Minion: They're immune to everything short of a Chaos Card, and are destroyed when the room is cleared/all buttons are pressed.
Punny Name: Mock + oculus.

Gasbag

Debut: Repentance

Stationary gaseous lumps that create poison clouds and spawn flies.

Deadly Gas: They create large clouds of toxic gas that slowly fill up the room. If Isaac stands in the gas for too long, he starts taking damage.
Mook Maker: Occasionally spits out a couple Army Flies.

Characters / The Binding of Isaac - Enemies

Edit Locked

Flies

Black Fly/Attack Fly/Ring Fly/Moter/Swarm Fly/Dart Fly/Army Fly/Hush Fly

Level 2 Fly/Full Fly

Willo/Level 2 Willo

Pooter/Super Pooter/Tainted Pooter

Bulb/Bloodfly

Fly Bomb/Eternal Fly Bomb

Boom Fly/Red Boom Fly/Drowned Boom Fly/Dragonfly/Bone Fly/Sick Boom Fly/Tainted Boom Fly

Sucker/Spit/Ink/Soul Sucker/Mama Fly/Tainted Sucker

Eternal Fly

Humanoid

Gaper/Frowning Gaper/Flaming Gaper/Cyclopia/Deep Gaper/Blurb/Rotten Gaper/Dead Isaac/Twitchy/Blue Gaper/Greed Gaper

Pacer/Gusher/Black Globin's Body

Gurgle/Splasher/Crackle

Wraith/Null

Horf/Psychic Horf/Sub Horf/Necro/Tainted Sub Horf

Hopper/Flaming Hopper/Leaper/Eggy/Sticky Leaper/Tainted Hopper

Maw/Red Maw/Psychic Maw

Mr. Maw/Mr. Red Maw/Mr. Mine/Swinger

Skinny/Crispy/Rotty

Danny/Coal Boy

Bony/Black Bony/Revenant/Quad Revenant/Big Bony/Holy Bony

Clickety Clack

Maze Roamer

Fatty/Flaming Fatty/Pale Fatty/Bubbles/Bloaty/Fat Sack/Blubber/Half Sack/Conjoined Fatty/Quakey/Vis Fatty/Peeping Fatty/Stoney/Cross Stoney/Blue Conjoined Fatty/Shady/Gutted Fatty

Mulligan/Mulligoon/Mulliboom/Nest/Hive/Drowned Hive/Prey/Mullighoul/Gas Dwarf/Bouncer/Leper/Swarmer/Holy Mulligan/Tainted Mulligan

Blaster

Globin/Gazing Globin/Dank Globin/Black Globin/Cursed Globin/Cohort

Knight/Selfless Knight/Floating Knight/Loose Knight/Brainless Knight/Black Knight/Bone Knight

Vis/Double Vis/Chubber/Scarred Double Vis/Vis Versa/Evis

Faceless/Fanatic/Tainted Faceless

Bishop

Whipper/Snapper/Flagellant

Baby/Wrinkly Baby/Angelic Baby/Unborn

Dople/Evil Twin

Keeper/Hanger

Mole/Fred/Tainted Mole

Buttlicker/Butt Slicker

Goat/Black Goat

Homunculus/Begotten

Level 2 Gaper/Level 2 Horf/Level 2 Gusher

Worms and Grubs

Maggot/Small Leech/Small Maggot

Charger/Drowned Charger/Dank Charger/Carrion Princess

Level 2 Charger/Elleech

Spitty/Conjoined Spitty/Tainted Spitty

Leech/Kamikaze Leech/Holy Leech/Adult Leech

Grub

Round Worm/Nightcrawler/Tube Worm/Fire Worm/Roundy/Ulcer/Tainted Round Worm/Tainted Tube Worm

Para-Bite/Scarred Para-Bite/Cod Worm

Needle/Pasty

Fistuloid

Spiders

Spider/Strider/Swarm Spider/Big Spider

Level 2 Spider/Ticking Spider/Migraine

Baby Long Legs/Small Baby Long Legs/Crazy Long Legs/Small Crazy Long Legs

Rock Spider/Tinted Rock Spider/Coal Spider

Wall Creep/Blind Creep/Rage Creep/The Thing/Soi Creep/Tainted Soy Creep

Trite/Ragling/Rag Man's Ragling/Blister

Poop

Dip/Corn/Brownie Corn/Big Corn/Drip

Squirt/Dank Squirt/Splurt/Hardy

Dinga

Dump/Dump Head

Poot Mine

Fly Trap

Henry

Other

Clot/I. Blob/Ministro

Clotty/Grilled Clotty/Cloggy/Mega Clotty

Gyro/Grilled Gyro

Host/Red Host/Walking Host/Walking Red Host

Meatball

Brain/Poison Mind/Pon/Black Globin's Head/Festering Guts/MemBrain

Guts/Scarred Guts/Slog/Cyst/Mama Guts/Dead Meat

Poky/Slide/Wall Hugger/Grudge

Spikeball/Ball and Chain/Singe's Ball

Stone Grimace/Vomit Grimace/Cross Grimace/Gaping Maw/Broken Gaping Maw/Constant Stone Shooter/Stone Eye/Brimstone Head