"You may refer to me as 'Master', or 'Overlord of the Nine Circles of Infernus'! Bow to me, or taste my wrath. I am lord here, and I will not be denied!"
Overlord Laharl is the son of King Antroklis, and the lesser prince of Infernus, second to Satan.
During the events of the Hellmouth Conflict, he scolded Satan for his sloth and lack of presence in the other realms. Laharl ordered his lord to step down from the Throne, and Satan did, to give the young Overlord a chance. Laharl's forces opened "Hellmouths" across Mundus, from which his daemonic hordes poured out and besieged Atmah for an extensive amount of time, killing everything in their way. Though he found great success, he was thwarted by Blue Team.
He played his hand once again during the War of Pawns, where his minions battled against the forces of Malefor. Though he lost, his High Mages unleashed the hellfires and burned parts of the world to ash (this began the Wasteland Wars). Later, he joined the Mythic Dawn, where he served Veigar the Dark Champion. At the end of the Mythic Dawn War, when Veigar killed Laharl's father, Antroklis, Laharl fought and kiled Veigar, ending his threat to Existence.
After Laharl's "failure" during the Mythic Dawn War, Satan dethroned Laharl from Overlord status and brought him back to Prince status. Laharl, no longer in charge of Hell's armies, is now no longer considered a threat.