Werewolves are a hostile mob, part of the Mo' Creatures mod
Werewolves, as usually portrayed, have two forms- Human and wolf. The Human form wanders around aimlessly during the day, not interacting with the player other than looking at them. If killed, they drop wooden tools and sticks. But when the night comes, they transform into the more intimidating Wolf form. These will run after the player and attempt to attack them, sprinting on four legs occasionally. When killed, they drop stone and/ or iron tools and golden apples. When it becomes day again, they will turn back into humans if the player has not killed them.
Werewolves are extremely resistant against any tool except a gold sword. It is reccomended to keep a couple of them in your inventory, as they break easily. A gold sword will kill them in 3-4 hits, while any other tool takes much longer to kill them.