Suggestions by @markclaunch

Skai Jackson

as Flaxx in Once... The Book of Merlin

Joseph Gordon-Levitt

as Novak in Once... The Book of Merlin

Zachary Quinto

as NoNac in Once... The Book of Merlin

Elle Fanning

as Zara in Once... The Book of Merlin

Wallace Shawn

as Zoozle in Once... The Book of Merlin

Sabrina Carpenter

as Friggs in Once... The Book of Merlin

Djimon Hounsou

as Fraggs in Once... The Book of Merlin

Björk

as Wattle in Once... The Book of Merlin

Ben Kingsley

as King Pellinore in Once... The First Book of Arthur

William H. Macy

as King Mark in Once... The First Book of Arthur

Dragon

as Kaliden - The Dragon in Once... The Book of Merlin

Harrison Davis

as Young Sir Dagonet in Once... The First Book of Arthur

Donnie Yen

as Wu-Xi in Once... The First Book of Arthur

Lizzo

as Jatell in Once... The Book of Merlin

Ewan McGregor

as Whittle in Once... The Book of Merlin

Alan Tudyk

as Odo the Odo in Once... The First Book of Arthur

Warwick Davis

as Balor the Mighty in Once... The First Book of Arthur

Dev Patel

as Jibrīl in Once... The First Book of Arthur

Krysten Ritter

as Annowre the Sorceress in Once... The First Book of Arthur

Rihanna

as Mabb the Black in Once... The First Book of Arthur