In the mirror universe, Richard Galen was a Terran archaeologist, and the mentor of Jean-Luc Picard during the 24th century. Galen was entirely self-educated, although Picard felt that Galen knew more about his field than most scientists in the Klingon-Cardassian Alliance. Galen proposed a theory that the Klingons and the Cardassians shared a genetic heritage with the Terrans, which proved incredibly unpopular in the Alliance. As a result, he was executed for sedition. No Alliance scientists were willing to follow up on Galen's research, nor was Picard's Alliance benefactor, Gul Madred, willing to expend any resources on the matter.
In 2371, Picard used Galen's name as an alias, first when approached by Romulans near Iconia, and later when pretending to be an agent of the Obsidian Order to destroy the Borg at Rura Penthe. (TNG - Mirror Universe novella: The Worst of Both Worlds)