Exodus

Exodus is the main villain of Ultima III, and the "child" of Mondain and Minax.

Exodus is part Daemon, part magical entity, and part machine. Exodus was created by Mondain and Minax. The Daemon is the psyche, all the living things in it, while the machine was the power and knowledge, like a hard drive, called the Dark Core. Exodus waited a long time after the death of his creators, gathering information. Most of it was trivial, like the color of the sky at one specific day, while other information was about how to manipulate the very being of the world itself.

In Ultima III, Exodus attacked, poisoning the spirit of the land itself, while his hordes roamed Sosaria. He himself was safe on the Isle of Fire, protected by the Great Earth Serpent, which he had ripped out of the void. The last thing in turn caused the War of Imbalance on the Serpent Isle. His end came when the Stranger together with his/her companions used the Four Cards to destroy the machine part of Exodus.

But even this wasn't the end of Exodus. His psyche was fused by the Gargoyles into the Shrine of Diligence, where the Avatar found him in Ultima VI. Exodus by now regretted what he had done, having had enough time to think about it.

His left over machine part, the Dark Core, reappeared in Ultima VII. It being a artifact of unsurpassed evil, the Avatar managed to throw it into the void, preventing it from reattaching the psyche to it.

Trivia

 * The Four Cards needed to destroy Exodus are computer punch cards, showing Exodus' technological origins.