Yes, he was the king before lucifer

AAMON; AAMON; MALE; ??? OWL SNAKE DEMON HYBRID; LAWFUL EVIL; FLIGHT, STRENGTH, AN EARDRUM DESTROYING SCREECH; GOD, ANGELS, HIS DISOBEDIENT SERVANTS, USURPERS; SEEING HIMSELF AS A GOOD KING; AAMON WAS ONE OF THE FIRST DEMONS TO EVER EXIST AND BE CAST DOWN TO HELL. HE EVENTUALLY FORGED THE STAFF OF HELL (AKA, THE STAFF LUCIFER HOLDS) AND HE CALLED HIMSELF KING, UNTIL SOME OTHER DEMONS KILLED HIM TO TRY AND TAKE HIS RULE.