Werewolf

XP - ?
Drop as Werewolf - Golden Apples, Iron Tools
Drop as Human - Sticks, Stone Tools, and Wooden Tools
Heath - 30 Werewolf,
Attack - 4 and a half hearts
Spawn - Rare

Summary

It alternates between passive and aggressive states during the day and night respectively. Although in some nights there are different type of wolves that are often mistaken for werewolves but these are easily slaughtered. Werewolves are extremely hard to kill without the correct weapons.

Behaviour

During the day the werewolf is in a human form dressed in ragged clothing. It occasionally shouts "Help me!". When they are hit, they yell or say "Stop it! You're hurting me!", and will not attack in return.

At night, the human appears as if it is taking damage for around 3 seconds, before transforming into a humanoid wolf with a puff of smoke. They can be easily harmed with gold tools - other weapons will hurt them, but take much longer. Werewolves have the ability to sprint while walking on four legs. They also are able to move very fast upon chasing the player onto ice. This is useful if being pursued because the werewolf will slide very far away, making them no longer a threat, as long as you can shuffle around to avoid them. Alternative methods of killing a werewolf include fire, lava, TNT, tesla coil, cactus and long falls. Never try to fight them with something like a stone sword or something like that since it will kill you many times over before you can kill them.

The human form can drop wooden sticks and tools, the wolf can drop stone and iron tools, as well as golden apples.

Notes

• This is the first mob in a mod, and Minecraft, to be able to shapeshift into another mob.
• The werewolf in wolf form cannot easily fit through single block entrances

Source - Minecraft Forums