A Vampire because I like them.
A real one, not the Twilight vampires because that stuff is horrid.
Second choice would be a witch like in Harry Potter.
I'd be a hydra. Cut off one head, another grows in its place XD. And it can only be killed by the head of Medusa.
I would want to be a dragon. They are such a mystery and just with the amazing ability, specifically to fly, it would just be so cool!
A unicorn because unicorns are unicorns, and unicorns are awesome, because they are unicorns, and unicorns are unicorns, because unicorns are awesome.