Pee-Wee Herman (a.k.a. Paul Reubens) is set to appear in the December 3 episode of DC's Legends of Tomorrow on the CW, according to the show's writers room Twitter.
So...let’s talk Ep 407 for a minute. Or an hour. Because there is a surprise appearance made by the one and only @peeweeherman!!!— LoT Writers Room (@LoTWritersRoom) November 27, 2018
Assumably this would be Reubens in-character as Pee-Wee Herman, but Reubens has used the Pee-Wee Herman Twitter account when not in character. the DC's Legends of Tomorrow episode he will appear in is titled "Hell No, Dolly!".
"Rory and Ava are at odds; Sara tries to come up with a way for them to get along; a new magical creature attacks the Legends," reads Cw's description of the episode. "Constantine is forced to confront his tragic past but it could have devastating consequences for the rest of the team."
Reubens has played several roles in various film and TV adaptations of comic books including the Penguin's father in Batman Returns, the Spleen in Mystery Men, Jokey Smurf in the two Smurfs movies, Bat-Mite in Batman: The Brave & the Bold, and Elijah Van Dahl in Gotham.