Orkhepaj: Mine is Kurgan from Highlander.
Looks epic and still just a harder to kill human. Best is his scary side is just how little he cares about others, not some superpower. And we all know there are some like that, and we could run into one any day.
I think the best thing about the Kurgan is that he isn't exactly
evil, at least not in the way most villains are. He's not after power or money or revenge. He has no grand plan. All those things are pretty much meaningless to him. He just wants to have fun, and for him that's fighting and taking whatever he wants in the moment. He literally predates any ethics. He even dies with a smile, because he had a good run and winning never really mattered to him much.
Still, my favourite of all time would probably be Khan. KHAAAAN! Honestly, Ricardo Montalban is just superb in the Wrath of Khan. I can't think of any other villain whose pure hatred of the protagonist would be so palpable. And he just revels in it. It's pretty much the only thing that keeps him going, and he knows it.
"I've done far worse than kill you, Admiral. I've hurt you. And I wish to go on hurting you. I shall leave you as you left me, as you left her: marooned for all eternity in the center of a dead planet, buried alive. Buried alive." - that's just stuff of villain legends.