I, too, was going to say Count Petofi.
SPOILERS
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Anyone else with "powers" was a witch or warlock or something (vampire, phoenix) and had a reason to have powers. Petofi was apparently a mortal human being, but he somehow possessed awesome powers.
SPOILERS...
He may have been mortal at one time, like Angelique, but by the time he came to Collinsport, IMO, he hadn't been mortal for quite some time. He had powers independent of his famous "hand" -- for example, the talents he bestowed on Charles Delaware Tate, and the charm on Quentin's portrait -- and IIRC, no trace of him was found after he supposedly perished...just those funny blue glasses. He may have legitimately lost them in his haste to escape, or he could have left them behind as a red herring, but I think that if the series had continued, the character would have returned in a later storyline.
Cheers,
Linda