Yawgmoth

Yawgmoth was (and to many hopefuls, including myself, is) a pre-mending planeswalker who also happened to be the guy behind the original Phyrexia. TL:DR, he was a god, who had a whole plane of existence to call his own. Said plane of existence quickly became known as the Phyrexian Empire, with the signature "thing" as hordes of bio-mechanical warriors, demons, and monstrosities (Think a more grimdark AdMech with some sorcery thrown in, and you'll have a general idea) He also tried to take over Dominaria a few times (I think it was three) and kept doing evil things until he was killed by Urza and an alliance of planeswalkers. (This article is currently under construction).