Horned King

The Horned King is an antagonist in The Chronicles of Prydain series. He appears only in the first book, The Book of Three. He is Arawn's champion and the War Leader of Annuvin. The Horned King is described as a huge man wearing armor (except for his arms, which are naked and stained crimson), a red cape and an antlered skull mask. The antlers are presumably where he gets his name.

Arawn sends the Horned King to capture the oracular pig Hen Wen from Caer Dallben. He follows Taran across Prydain in search of the pig Hen Wen, but cannot find her. In the end, he marches his army to Caer Dathyl and attacks Taran when he and Eilonwy try to warn the Sons of Don of the impending attack. Taran tries to fight him with the sword Dyrnwyn, but is nearly slain by the sword's fire in his attempt to draw it. Gwydion is able to defeat the Horned King by speaking and uttering his true name (Cornelius presumably), and upon the utterance of his name, the Horned King is being struck by a flash of lightning and destroyed by flames.

The Black Cauldron
The Horned King is the main antagonist in the Disney's 1985 animated film, The Black Cauldron''. ''He is voiced by John Hurt.