They first appear in Chapter 2.
They are round, bat-like monsters with pair of fangs, short wings, and red eyes.
Fat Bats move slower than their normal variants but with higher health. They will shoot a bullet-shot at Isaac when he aligns diagonally. Fat Bats will also try to dodge Isaac's attacks.
- Fat Bat is the first Afterbirth enemy to be revealed during the DLC's development.