Suggestions by @chrisdeaver

Mark Hamill

as Springtrap in Gravity Falls Return

Kermit the Frog

as Guest Stars in Gravity Falls Return

Grover

as Guest Stars in Gravity Falls Return

Abby Cadabby

as Guest Stars in Gravity Falls Return

Cookie Monster

as Guest Stars in Gravity Falls Return

Elmo

as Guest Stars in Gravity Falls Return

Big Bird

as Guest Stars in Gravity Falls Return

Wonder Woman (DC Extended Universe)

as Guest Stars in Gravity Falls Return

Superman (DC Extended Universe)

as Guest Stars in Gravity Falls Return

Batman (DC Extended Universe)

as Guest Stars in Gravity Falls Return

Bugs Bunny

as Guest Stars in Gravity Falls Return

Finn Mertens

as Guest Stars in Gravity Falls Return

Princess Peach Toadstool

as Guest Stars in Gravity Falls Return

Waluigi

as Guest Stars in Gravity Falls Return

Wario

as Guest Stars in Gravity Falls Return

Luigi

as Guest Stars in Gravity Falls Return

Super Mario

as Guest Stars in Gravity Falls Return

Peter Parker/Spider-Man (Raimiverse)

as Guest Stars in Gravity Falls Return

Black Widow (Marvel Cinematic Universe)

as Guest Stars in Gravity Falls Return

The Incredible Hulk (Bruce Banner)

as Guest Stars in Gravity Falls Return