Suggestions by @axiomman

Elton John

as Songwriter in The Rayman Movie

Doug Walker

as That Guy Who Shows Up In the Climax As a Cameo in Zack Snyder's Wish

Dee Bradley Baker

as The Gump in Land of Oz

Super Mecha Death Christ 2000 B.C. Version 4.0 BETA

as SUPER MECHA DEATH CHRIST 2000 B.C. VERSION 4.0 BETA in Zack Snyder's Wish

Alan Silvestri

as Composer in Sonic (1994)

Charlie Day

as Valentino in Zack Snyder's Wish

Brian Blessed

as Zandoz in Zack Snyder's Wish

Rob Walker

as Santa Christ in Zack Snyder's Wish

Phelan Porteous

as Phelous in Zack Snyder's Wish

John Mulaney

as Big Jack Horner in Zack Snyder's Wish

Matt Damon

as Dayman in Zack Snyder's Wish

Spoiler

as Dayman in Zack Snyder's Wish

Robbie Rist

as The Eee Tee in Zack Snyder's Wish

Angelique Cabral

as Amaya in Zack Snyder's Wish

James Rolfe

as Narrator in Zack Snyder's Wish

Chris Pine

as Magnifico in Zack Snyder's Wish

Jack Black

as Jack Black Panda in Zack Snyder's Wish

Keith David

as Kaiser Hordak in Zack Snyder's Wish

Avan Jogia

as Star in Zack Snyder's Wish

Lloyd Kaufman

as Producer in Zack Snyder's Wish