Grod, from Ultima VII
During the Avatar's quest to foil the Guardian's plans in Ultima VII, the Avatar encountered Grod the Troll near the prison cells of Sullivan and Anton. Grod revealed himself to be a true monster, who mostly did his job because he enjoyed torturing people, complaining that Anton denied him the screams of pain that he so enjoyed.
The party killed Grod and freed Anton with his keys. However, Sullivan was not freed, since he deserved to rot in prison.