Selvyn is a dark Mage in Ultima VII. He and his band of Rebels have their headquarters in rooms above the dungeon Shame. They plan to assassinate Lord British, but the Avatar caught them in their meeting room, and killed them all, stopping the plot.
Selvyn also has a tower west of Serpent's Spine, where a lot of good equipment is found. One of the teleporters in his room leads to the orchard just west of Castle British.