Bio: Dominus is a highly advanced sentient super-computer complex of machinery created by the Quists (also known as "The Arcane") and controlled by Lucifer. Dominus was the channel by which this alien race named "The Arcane" conquered planet after planet. He first appeared in The Uncanny X-Men # 21 (June 1966) entitled "From whence comes... Dominus?"; however, he was first mentioned on The Uncanny X-Men # 20, the one on which Professor Charles Xavier reveals a secret to Jean Grey by telling her one of the great reasons he founded the X-Men: to one day meet the further threat of Lucifer.
At Lucifer's command post, the Supreme One checks in with his Agent, Lucifer, and says that the time is ready for his true purpose, which is to deploy Dominus. Dominus and Lucifer were temporarily defeated by Charles Xavier, who suffered a debilitating injury in the process. Xavier's X-Men would later defeat Lucifer.