Babies are monsters encountered in Chapter 3 and 4.
Behavior
Babies slowly float towards Isaac, occasionally shooting a single blood shot. They also have the ability to teleport to anywhere in the room, occasionally close to Isaac. They usually teleport after a shot. The only random element is the shooting, and they have no specific cue to indicate incoming attacks.
Champion Variant 
Eternal Baby acts similar to original Baby, but will leave 4-way bullets in "+" pattern when teleporting.
This variant was added in the Eternal Edition update for the Wrath of the Lamb expansion but exclusively encountered in Hard Mode.
Trivia
- Version 1.33 introduced a bug called "Psy Baby" which was fixed in 1.4
- Normal Babies or Angelic Babies could spawn with the ability of firing homing shots similar to the Psychic Maw and the Spoonbender item.
- Babies always spawn in pairs or fours. The lowest spawning babies in each room were always the psychic ones, whether normal or angel. This also applied to Isaac and ??? spawning 2 angel babies; each time they were spawned, the lower one of the two would be psychic.
- Babies use the same death sounds as gooballs from the game World of Goo.
Bugs
- If you touch the Baby right when it reappears (after disappearing to teleport), you will take no damage.