Dispater

Dispater is an archdevil of the Nine Hells, and the Lord of the Iron City of Dis. Paranoid and reclusive, he no longer leaves his inner sanctum. He is always stoic and nonexpressive, emotionless, expressionless, remaining completely calm beyond the fault even in battle.

Background
Dispater, along with Mephistopheles, was once an ally of Mammon, but Mammon betrayed them both.