Robin Williams; Lizzy Caplan; Icona Pop From "The Crazy Ones", actor Robin Williams; from "Masters of Sex", actress Lizzy Caplan; an opera Top Ten List presented by soprano Renée Fleming; musical guests Icona Pop. Details Casts Title Robin Williams; Lizzy Caplan; Icona Pop Genres Talk Comedy Release Date 2013-09-25 Episode Runtime 01 Hours 03 Minutes Season Number 20 Episode Number 129 Production Companies Worldwide Pants, CBS Entertainment Productions, CBS Productions, CBS Studios David Letterman Self - Host Paul Shaffer Self -Musical Director Alan Kalter Self - Announcer (voice)