Basileus is the final of the three Dead Lords that Death must defeat and bring to the Lord of Bones in Darksiders II. Although sworn to serve the Undead King, the Dead Lords abandoned their duties and went in search of Corruption.
When Death comes to the Kingdom of the Undead seeking the Well of Souls, the Lord of Bones charges Death with retrieving the Lords and bringing them back to him in exchange for locations of the Dead City. Once defeated, Basileus returns with Death to the Undead King, who executes the Lords for their betrayal.