Mondain

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 Mondain alive and slew him before all of the world was conquered.

Nevertheless, something strange happened, which has never been explained in the series. Three of the four continents of the world apparently disappeared after Mondain's death. Some form of magic prevents anyone from arriving at the other continents. Sometimes lost ships arrive from the other continents, to never be able to go back to where they came from.

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).