Lyran the lich from Baldur's Gate: Dark Alliance 2. Not only does he live in a huge mansion, he is pretty much invincible. I mean, I beat him, but still. He can't be killed, you have to destroy his remains, which are inconveniently stored in urns all around the house. And meanwhile, he has tons of super powerful spells.
Dagoth Ur from Morrowind, sure he died at the end but leading armies of undead zombies and other killer creatures against the forces of the imperial and morrowind army and then dying in the final showdown versus the nervarine!!!!!!