Baelgar
Rebellious Archfiend Warlord
An Archfiend Warlord under Nulgath, Baelgar rebelled because he wanted freedom from his contract. Though he had power and glory, he believed neither truly belonged to him while another owned his soul. He wanted to win something of his own, not seize Nulgath's throne.
Dage defeated Baelgar in the Seven Circles, and the Commandant ordered him taken for judgment. Baelgar's words stayed with Dage, helping him recognize his own desire to escape his master's shadow.
Sources
Dage the Lich's dialogue · Dage the Lich's quests · Fiend Past map