Yes, none other than Red Foreman himself turned up on The X-Files during the show's early years, in the season three episode Grotesque. In the episode, Smith plays FBI agent Bill Patterson, a sort-of former mentor to Fox Mulder who feels he has wasted his talents working on the X-Files unit. Only, drawn into darkness himself, he reaches out to Mulder for help with a case of a macabre nature. For viewers of a certain age (perhaps too young to remember him in RoboCop) this might have been their first exposure to Smith in a serious role, and he fits in perfectly in the X-Files universe. In fact, it's rather sad that this role had to be a one-off appearance.