Dullahan

A Dullahan is a humanoid monster, cloaked in purple and riding half of an undead horse. It swings a sword around in the air while riding back and forth.

A later incarnation was a monster resembling a large suit of armour with no helmet. Wielding a lance, and orbited by a floating, grinning head, this boss attempted to slash and stab the character into submisison. The boss unleashes its most powerful attacks when its head flies back to the body, allowing it to throw dark energy projectiles.