Alchemist potion on Undead
An Undead player will become either a Wight or a Ghoul.
Actually, believe it or not, but an undead purged by the alchemist was once turned into a villager role. Would love to hear an update from the mods if this no long happens anymore.
Source: A spud I hosted long ago. Can't remember the number right now, but I'll update the answer once I check the archives.