Death Knight

When a paladin that falls from grace dies without seeking atonement, dark powers can transforn the once mortal knight into a baleful undead creature. A desth knight is a skeletal warrior clad in plate armour. Beneath its helmet, one can see the knight's skull with malevolent pinpoints of light burning in its eye sockets.
The death knight retains the ability to cast divine spells, but no death knight can use its magic to heal. It also atracts and commands lesser undead, although death knights that serve powerful friends  might have fiendish followerrs instead. Death knights often use warhorse skeletons and nightmares as mounts.
A death knight can arise anew even after it has been destroyed. Only when it atones for a life of wickedness or finds redemption can it finally escape its undead purgatory and truly perish.