Sir Zeliek

Sir Zeliek is an undead paladin who seemingly resisted being turned into a Death Knight like the other Horseman of Naxxramas due to his powerful faith in the Holy Light despite all attempts of Kel'Thuzad's corruption. Sadly however his body was still forced to obey the Lich King's damnation. This could be seen as a mark of great spirituality and mental strength on the part of the paladin.