Suggestions by @silmarils

Elizabeth Olsen

as Vaire in The Silmarillion

James Phelps

as Amras in The Silmarillion

Oliver Phelps

as Amrod in The Silmarillion

Hugh Jackman

as Ulmo in The Silmarillion

Elizabeth Henstridge

as Yavanna in The Silmarillion

Richard Madden

as Beren in The Silmarillion

Liam Hemsworth

as Turin in The Silmarillion

Daisy Ridley

as Luthien in The Silmarillion

Ben Barnes

as Maeglin in The Silmarillion

Hattie Morahan

as Nienna in The Silmarillion

Paul Bettany

as Morgoth in The Silmarillion

Chris Hemsworth

as Tulkas in The Silmarillion

Marion Cotillard

as Varda in The Silmarillion

Michael Fassbender

as Melkor in The Silmarillion

Liam Neeson

as Manwe in The Silmarillion

Tom Hiddleston

as Fingolfin in The Silmarillion

Harry Lloyd

as Feanor in The Silmarillion

Sylvester McCoy

as Radagast in The Silmarillion

Lee Pace

as Thranduil in The Silmarillion

Hugo Weaving

as Elrond in The Silmarillion