Ghouls

Ghouls are Hardmode Underground Desert and Desert enemies. They follow the Fighter AI (behaving similar to Zombies). Ordinary Ghouls spawn inside the normal Desert and the Tainted Ghoul spawn during a Crimson desert, the Vile Ghoul inside a Corrupted desert and the Dream Ghoul inside a Hallowed Desert.

Trivia

 * Terraria's Ghouls are probably based on the ghouls of the Cthulhu Mythos, which have long, pointed ears, dwell in cave systems, and are sometimes born from transformed dreamers.

History
Goules