Suggestions by @markclaunch

Tom Holland

as Sir Galahad in Once... The Second Book of Arthur

Maisie Williams

as Sister Elenne (Nun) in Once... The Second Book of Arthur

Joan Cusack

as Morgausa in Once... The Second Book of Arthur

Dacre Montgomery

as Sir Mordred in Once... The Second Book of Arthur

Liam Neeson

as King Gorlois in Once... The Second Book of Arthur

Tim Roth

as Sir Agravain in Once... The Second Book of Arthur

Christopher Eccleston

as King Anguish - King of the Fey in Once... The Second Book of Arthur

Helena Bonham Carter

as Queen of Fey in Once... The Second Book of Arthur

Lena Olin

as Queen Igraine in Once... The Second Book of Arthur

John Boyega

as Sir Hector in Once... The Second Book of Arthur

Sean Bean

as King Uther Pendragon in Once... The Second Book of Arthur

Ian McShane

as King Pelles (Fisher King) in Once... The Second Book of Arthur

Dave Bautista

as Sir Percial in Once... The Second Book of Arthur

Anya Taylor-Joy

as Nimue in Once... The Second Book of Arthur

Sean Bean

as King Pelles in Once... The Second Book of Arthur

Shawn Ashmore

as Sir Gawain in Once... The Second Book of Arthur

Aaron Ashmore

as Sir Tristian in Once... The Second Book of Arthur

Natalie Dormer

as Morgause in Once... The Second Book of Arthur

Henry Cavill

as Sir Lancelot in Once... The Second Book of Arthur

Peter Dinklage

as Sir Dagonet in Once... The Second Book of Arthur