Nice! I’m going to up-vote the Lich – the first recurring foe I ever used in D&D was a Lich, originally just rolled up in a procedurally generated dungeon, from a random monster table.
Downvote is for the Will-o’-Wisp. No one falls for that one anymore.
Alhoon 20
Allip 17
Banshee 22
Beholder Zombie 20
Bodak 20
Bone Naga 20
Boneclaw 20
Crawling Claw 20
Death Knight 20
Death Tyrant 20
Deathlock 20
Demilich 20
Dracolich 20
Eidolon 20
Flameskull 20
Ghast 20
Ghost 20
Ghoul 20
Gnoll (Witherling) 20
Lich 21
Mind Flayer Lich 20
Minotaur skeleton 20
Mummy 20
Mummy Lord 20
Nightwalker 20
Ogre Zombie 20
Poltergeist 20
Revenant 20
Shadow 20
Skeleton 20
Skull Lord 20
Spawn of Kyuss 21
Specter 20
Sword Wraith 17
Vampire 20
Vampire Spawn 20
Vampiric Mist 20
Warhorse Skeleton 20
Wight 20
Will-o’-wisp 17
Wraith 20
Zombie 17