Rodrick

Rodrick is a former member of the Knights of the Crux Ansata who had turned traitor, calling himself the "Chaos Knight."

Description
When investigating on the fourth level of the Abyss during Ultima Underworld I, the Avatar learned that both the Knights and the Trolls feared Rodrick, who was terrorizing the whole level. However, for the final quest to become a Knight, the Avatar had to confront Rodrick, since he had the only key to the needed item.

Rodrick gave a brief warning, then attacked. After a fierce battle, the fiend was finally slain. Dorna Ironfist was so impressed, that he gave the Avatar the Standard of Honor as a reward.

Trivia

 * The Ultima Underworld I Clue Book reveals that Tyball was quite proud to admit that Rodrick's evil had been his work, having slowly corrupted him over time into the monster seen in the game.