The most useful monster.

I adore the Witch (an evil Sorceress, referred to differently in various versions of the game). She's a beauty, and her spells – explosion, general slowdown, banishment, and teleportation – make her the best warrior-mage.
She's the best; I use her against everyone, even when outnumbered (she's only weak against archers like the Titan and Gargantua and hates Dungeon creatures!).

Djinn and Titan forever!