Westphall, who is autistic, played an increased role in "St. Elsewhere"s final episode, "The Last One", one interpretation of which is that the entire "St. Elsewhere" storyline exists only within Westphall's imagination. As characters from "St. Elsewhere" have appeared on other television shows and those shows' characters appeared on more shows, and so on, a "Tommy Westphall Universe" hypothesis (postulated by Dwayne McDuffie) argues that a significant amount of fictional episodic television exists within a fictional universe imagined by Tommy Westphall.