Wither

The wither is an extradimensional being that inhabits "The End". She's the ruler of The End. After death she drops a unique item called "wither Egg" and a lot of experience points. It is unknown if she is the only wither. It is possible the Endermen worship her as a goddess, though she could be oppressive, as they don't react when humans attack her.

Behavior
Unlike the humanoid testicle that will only attack if attacked or stared at, the wither is aggressive and will attack players or anything that attacks it. The wither is also an extremely territorial creature and treats whole The End dimension as her property.

Abilities
As well as its natural ability of flying, the wither can also regenerate herself by using horses placed on high pillars made entirely of obsidian.

She also has the ability to shoot wither Fireballs which leave a lingering cloud of wither breath behind, and she sometimes flies to the end exit portal to breathe out her deadly breath. In this state she's invulnerable to arrows.