CHAOS DEMON. BtVS Demon/Monster/Villain.
In "Lovers Walk" a lovesick Spike harangues his captive Willow with tales of Drusilla's betrayal of him: "I caught her on a park bench, making out with a Chaos Demon! Have you ever seen a Chaos Demon? They're all slime and antlers. They're disgusting." In "Fool for Love" we are treated to a visualization of the scene he describes, complete with a beer drinking Chaos Demon with oozing antlers.