Mondain was a fictional evil wizard in the first Ultima game and its main villain. Mondain intended to conquer the world of Sosaria. Fortunately, the Stranger, who would become the Avatar, destroyed the Gem of Immortality, which kept him alive and slew him before all of the world was conquered.
Nevertheless, only two places survived the subsequent backlash of magic, Britannia and Serpent Isle. The rest disappeared completely.
The wizard left behind his apprentice and lover, Minax (villain of the second game), and their offspring Exodus (villain of the third game) as well as the shards of his Gem (created the Shadowlords of the fifth game) and his skull (destroyed in the fourth game).