Giant Bat

Giant Bat is a bigger, healthier and stronger version of the Cave Bat. It uses the same bat AI and also spawns in the cavern layer. The Giant Bat can also afflict players with the Confused debuff, causing controls to reverse.

Like many mobs introduced in 1.1, the Giant Bat will only spawn after the Wall of Flesh has been defeated.

Trivia
The ability of the giant bat to confuse the player may be a reference to the Pokemon franchise, in which the Pokemon "Zubat" is notorious for confusing the players Pokemon.