Suggestions by @larryjg

Stephen Fry

as God in Monty Python's Spamalot

Emma Thompson

as God in Monty Python's Spamalot

Whoopi Goldberg

as God in Monty Python's Spamalot

Christina Aguilera

as The Lady of the Lake in Monty Python's Spamalot

Tom Holland

as Sir Robin in Monty Python's Spamalot

Tom Holland

as Sir Robin in Monty Python's Spamalot

Michael Palin

as Lord of Swamp Castle in Monty Python's Spamalot

Niall Horan

as Sir Robin in Monty Python's Spamalot

Anthony Hopkins

as Historian in Monty Python's Spamalot

Andrew Garfield

as Sir Lancelot in Monty Python's Spamalot

Eric Idle

as Not Dead Fred in Monty Python's Spamalot

John Cleese

as Tim the Enchanter in Monty Python's Spamalot

Daniel Radcliffe

as Sir Galahad in Monty Python's Spamalot

Troye Sivan

as Prince Herbert in Monty Python's Spamalot

Charlie Hunnam

as King Arthur in Monty Python's Spamalot