This holiday special goes back in time to show how Elmo's ancestors--not to mention those of Grover, Big Bird, Bert, Ernie, Oscar the Grouch and Cookie Monster--helped transform "the most unfriendly street in town" into the bright, kind, music-filled place … Audra McDonald, Zosia Mamet, Jim Gaffigan, Eric Jacobson, Matt Vogel, Alan Muraoka, Suki Lopez Added on HBO 2023-01-06.