If you know who I'm talking about, you get my question.
Obviously currently the best candidates for that title have to be young Jean and Magik. Their "Carrie" moments have been quite hilarious lately.
But IMHO the "mutant" Carrie has to be Scarlet Witch, what with her mental instability and potential for mass murder.
At a close second are the Cuckoos. Because if Wolverine manages to find them creepy, then there really is something creepy about them lol.
And then there's X-Man. He's a guy, and he's perfectly mentally stable. But he also was a walking psychic WMD for some time. Given the right amount of insanity and loss of control, he could have become a male "Carrie" :P