Tommy Westphall, portrayed by Chad Allen, is a minor character from the drama television series St. Elsewhere, which ran on NBC from October 26, 1982, to May 25, 1988. Westphall, who is autistic, took on major significance in St. Elsewhere's final episode, "The Last One", where the common interpretation of that finale 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 was postulated by Dwayne McDuffie where a significant amount of fictional episodic television exists within Tommy Westphall's imagined fictional universe.