 The permanent guest hosts were Joan Rivers (1983–86), then, after about a year where a wide range of guest hosts were used, Garry Shandling alternating with Jay Leno (1987–88) and finally Leno alone (1988–92) after Shandling left to focus on his Showtime series "It's Garry Shandling's Show".Though the concept of using "permanent" guest hosts was fairly strictly adhered to, occasionally illness or some other situation necessitated a substitute guest host, as when David Brenner filled in for Joan Rivers on October 31 and November 1, 1985, when Rivers's husband was briefly hospitalized.During the show's run, its cast and crew collaborated with a number of NBC sitcoms to produce spoof episodes of the "Tonight Show."