Gapers will walk towards Isaac by the most direct route possible. If there is no way to reach Isaac, due to obstacles such as rocks or poops blocking the way, they will stand still until a proper route is created.
Frowning Gapers look identical to regular Gapers, but have empty eye sockets that appear closed before they get close to Isaac. When awake, they have the same head sprite as Horfs. Frowning Gapers move quicker than Gapers, and the chance for them to turn into Pacers or Gushers is higher.
Flaming Gapers behave identically to regular Gapers, though they move at a faster pace, but not as fast as Frowning Gapers. They appear to be on fire, but despite this they aren't negatively affected by it in any way. They mainly replace most of the regular Gapers in the Burning Basement.
The Cyclopia moves slower than normal Gapers, but leaves behind a short-lasting trail of Red Creep and occasionally fires a blood shot towards Isaac.
Gurgles are considerably tougher enemies that look identical to Frowning Gapers aside from their green coloration, and are very common in Catacombs. When they get near Isaac, they fire an Ipecac shot at him. Killing it has a small chance for it to become a Splasher. These shots will kill other enemies in their Area of Effect, but Gurgles themselves are immune to their own shots.
Like other enemies' explosive projectiles, Gurgles' shots can be used to shatter Rocks or open Secret Rooms by making them fire at the appropriate area.
Gurgles are somewhat more predictable and accurate in their shots compared to Guts and Walking Guts, because they will always shoot at Isaac's position. However, the timing of their shots is unpredictable. As such, an effective strategy of delivering explosives to a particular area (e.g. tinted rock or potential Secret Room entrance) is to stand still in that position as long as possible before moving to avoid getting touched, to prompt the Gurgles to shoot their projectiles at you.
In Repentance, Gurgles have a hunched posture, like how they did in the original game.
Crackles are a variant of Gurgles found only in Ashpit. They walk towards Isaac similar to a Gurgle, but instead of shooting an explosive shot, they shoot a ball of fire that releases 4 lines of fire in all cardinal directions when it touches the ground.
- In Chapter 3, Nulls are most commonly encountered in a 2x2 room layout, where six of them are encased in the center, unable to chase Isaac. Isaac has to blast away some skulls first to open the path to them. Flight, as well as spectral tears, do very well here, as the player can fly in, drop a bomb, and leave, and the enemies will remain stationary where they were last chasing the player.
- White Champion Nulls may not be able to turn invisible while invincible.
- They are referred to as "Nulls" in the bestiary, which goes both for its singular and plural usage.
Greed Gapers behave similarly to regular Gapers and are spawned during the Ultra Greed boss fight.
2 Greed Gapers may rarely replace the shopkeeper in Shops.
2-4 Greed Gapers have a chance to appear in Treasure Rooms.
- Greed Gapers no longer appear in treasure rooms and are replaced by Bulbs. They can, however, still appear in certain Super Secret Room layouts. Greed Gapers can also appear in Ultra Secret Rooms.
Deep Gapers are a new Gaper variant that appear in Downpour and Dross. They will emerge from the floor once all previous enemies on certain room have been killed. Deep Gapers behave like normal Gapers after emerging.
This enemy has 14 design variants, 7 for the Downpour floor and 7 for the Dross floor. These variants are purely cosmetic with the exception of one that has a Small Leech sticking on its head, which will detach from it and chase Isaac when the Gaper is killed.
Blurbs appear in Downpour and Dross, with a different appearance for either environment. They initially walk slowly towards Isaac, but after taking some damage or getting close to him, will release the projectiles stored in its mouth as a chaotic burst of tears. After firing their tears, they act like regular Gapers and chase Isaac faster than before, attempting to deal contact damage. They will still spit out their projectiles if killed in an instant with high damage, firing towards Isaac even if he is not being targeted.
Wraiths appear in Downpour and Dross with a different appearance for either environment. They behave like regular Gapers, but are detectable only by their reflections and the ripples they make in the water. The occasional lightning strikes in Downpour will also make them briefly visible.
They are visible in the Mirrored World, but their reflections will be invisible instead, appearing when lightning strikes.
Rotten Gapers are a variant of Gapers found only in Corpse. They chase Isaac faster than regular Gapers, and have slightly different behavior depending on their facial expression.
- If its eyes and mouth are normal, it chases Isaac slowly, at the speed of a regular Gaper. (ID 10.3.4)
- If it has a flattened eye, it chases Isaac slightly faster, at the speed of a Frowning Gaper. (ID 10.3.1)
- If it has an empty eye socket, it chases Isaac quickly, slightly slower than a Gazing Globin. (ID 10.3.2)
- If it has its eyes closed, it chases Isaac slowly, spawning Small Maggots once every two seconds up to a maximum of 6. (ID 10.3.3)
- If it has its tongue sticking out, it chases Isaac similarly to Lust, gaining speed as it moves but changes directions slowly, losing momentum as it does. This version will also not normally run into Isaac but instead runs around and maintains a distance to his position. (ID 10.3.5)
Mother summons a horde of Dead Isaacs at the bottom of the arena that walk up towards Mother. Once they reach Mother, she swipes at them, killing them, releasing a burst of blood shots, and launching their corpses towards Isaac.
After a while, she ends this attack by slamming down both hands, which causes a small rock wave to appear beneath any remaining Dead Isaacs, launching them up into the air.
Twitchies are a Gaper/Trite hybrid found only in Corpse. They alternate between chasing Isaac and rapidly leaping at him. They leap at Isaac 1-3 times before returning to chasing him on foot, and their leaps can target him from almost across an entire normal-sized room. Most leaps target Isaac's location though they will occasionally attempt to leap to where Isaac is moving. They can also occasionally leap away to dodge Isaac's tears.
Their heads also occasionally twitch violently (hence the name), although this is purely cosmetic.
Level 2 Gaper
Level 2 Gapers appear in the Corpse. They look like a large, decaying version of Frowning Gapers.
They behave much like Frowning Gapers, however once they take enough damage, they become split into a Level 2 Horf, which spits Small Maggots at Isaac, and a Level 2 Gusher, which runs around the room and spawns Small Maggots.
- Due to Dead Isaac only being encountered via one attack, it is possible to go multiple runs without finding them.
- This can be inconvenient, as Dead Isaac counts as a Bestiary entry.
- When the Head of the Keeper is picked up as Keeper, he will look similar to the Greed Gaper.
- The appearance of Cyclopias is reminiscent of the fatal birth defect of the same name, which is characterized by the failure of the embryonic prosencephalon to properly divide the orbit of the eyes into two cavities.
- A Stoney makes the same sound as a Large Champion Gaper.
- Frowning Gapers and Nulls don't make noises until they open their eyes and start chasing the player quicker.
- Greed Gapers are also known as Greedlings, a name given by a card of it from The Binding of Isaac: Four Souls, although it's seldom referred to as a "Greedling" by players.
- Gapers and Flies are some of the monsters with the most variations. The Gaper has 14 variations.
- Blurbs spawned outside of Downpour will be skin-toned
- Wraiths spawned in rooms without water will appear translucent.
- Twitchys in Antibirth have a more melty and greenish appearance than in Repentance.
- In Antibirth, Deep Gapers were referred to as Tidal Gapers.
|Bug!||If a Dark-Red champion Frowning Gaper does not become a gusher or pacer and reforms, the head won't appear until the Gaper sees the player. The same goes for a normal Gaper, however, the head won't appear once reformed.|
|Bug!||If an Explosivo tear is stuck to a Null when it becomes invisible, the tear will fall to the ground.|
|Bug!||Rotten Gapers don't appear in the Bestiary in any form.|
|Bug!||If a Champion Gaper is killed and it turns into a Pacer/Gusher, it will no longer be a champion.|
|The Binding of Isaac: Rebirth|
|Achievements||Attributes||Bosses||Cards and Runes||Challenges||Chapters|