It has 22 HP per segment.
The number of individual The Hollow bodies that can spawn each fight can vary from 1-4. The most common encounter with The Hollow is with 2 bodies.
- Flies around the room diagonally, bouncing off of walls.
- The Hollow appears to travel faster when moving at verticle angles compared to horizontal.
- The Hollow can change direction if it collides with Isaac.
- Occasionally spawns poop while moving.
- The Hollow's segments can be split into smaller copies of the boss as long as the new Hollow segments are longer than 2 pieces.
There is a chance that a Grub can spawn alongside a shorter Hollow (basically replacing a second Hollow).
Champion Versions 
- Dark Grey: 15% larger, has slower movement and 25% more HP (27.5). Each segment that isn't the head spawns a Boom Fly when killed. Does not spawn any poop.
- The head will spawn a Boom Fly only if killed immediately after spawning.
- Gold: 15% larger and has 25% more HP (27.5) but retains the same movement speed. Each segment that isn't the head will drop a coin on death.
- The head will drop a coin only if killed immediately after spawning.
- Green: Chance for each segment that isn't the head to spawn a Charger on death. Occasionally stops movement to shoot 3 bullets at wherever it is facing.
- The head will spawn a Charger only if killed immediately after spawning.
The Hollow as one of Delirium's forms.
- Poop spawned by The Hollow will never drop pickups, even when in possession of Petrified Poop.
- Poops spawned by The Hollow have an incredibly low chance to spawn pickups. This chance is not affected by Petrified Poop.
- Leaving the room and returning will make the poop generate pickups normally.
- Piercing tears make fighting The Hollow much easier, as each tear can damage multiple segments.
- Piercing shots no longer damage segmented enemies multiple times per attack.
- The Hollow was added in the Wrath of the Lamb DLC for the original The Binding of Isaac.
- It is the posthumous version of Larry Jr..
- The definition of hollow is empty on the inside or surface, which could explain the boss's paleness and complexion.
- The Hollow is the only boss that has three Champion versions.
- The Hollow is the only regular boss that can be spawned by Mega Satan between thresholds.
|Bug!||Sometimes this boss will get stuck in the wall when slowed.|
|The Binding of Isaac: Rebirth|
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