Suggestions by @lorog

Fionn Whitehead

as Timmy Turner in The Scary 🅾ddParents

Christopher Eccleston

as The Lich in The End of 🅾oo

Louis Partridge

as Marshall Lee in The End of 🅾oo

Awkwafina

as Cake in The End of 🅾oo

Hunter Schafer

as Fionna in The End of 🅾oo

Katherine McNamara

as Flame Princess in The End of 🅾oo

Tom Kenny

as Peppermint Butler in The End of 🅾oo

Shannon Purser

as Lumpy Space Princess in The End of 🅾oo

Robert Downey Jr.

as Simon in The End of 🅾oo

Karen Fukuhara

as BMO in The End of 🅾oo

Zendaya

as Marceline The Vampire Queen in The End of 🅾oo

Abbey Lee Kershaw

as Princess Bubblegum in The End of 🅾oo

Sam Rockwell

as Jake in The End of 🅾oo

George MacKay

as Finn in The End of 🅾oo

Dee Bradley Baker

as Gilbert in The Bald Bastard

Ralph Fiennes

as Future Caillou in The Bald Bastard

Spoiler

as Future Caillou in The Bald Bastard

Keri Russell

as Doris in The Bald Bastard

Dan Fogler

as Leo in The Bald Bastard

Robert Downey Jr.

as Boris in The Bald Bastard