Pet Bat

The Bat familiar is an item exclusive to the Xbox 360 and PS3 version of the game.

Key Features
The Bat familiar is summoned by consuming the Vial of Blood, Vial of Blood is an item that can be  found in chests scattered around the dungeon were you first encounter Skeletron

What the Bat does.
Just like all the other familiar, it will follow and fly wherever you go.