It was Dennis Miller (in the 1990s) who later brought Steve Allen back as a guest/co-host (for at least a week).
Late night tv didn’t even notice him.
And Screamin’ Jay Hawkins was on as bandleader.
Meanwhile, today’s nighttime shows don’t have any talent like that.
http://insidetv.ew.com/2013/03/20/jay-leno-reacts-monologue/