I'll chip in with Wendigo (Fiend Folio, I think?), a curse that turns you into a fey (rules for fey lifespans are left deliberately ambiguous, but immortal is one of the common paradigms) as a punishment for cannibalism. For the purpose of this thread, that makes essentially a less risky ghoul, as you don't have to die for the transformation, and can just keep committing acts of cannibalism until the curse takes. And if you get killed before that happens, you've still got decent odds of turning into a ghoul/ghast.