Suggestions by @silmarils

Nick Blood

as Hurin, Father of Turin in The Silmarillion

Score: -3

Jason Clarke

as Barahir in The Silmarillion

Score: +2

Morgan Freeman

as Eru Illuvatar in The Silmarillion

Score: +5

Burn Gorman

as Saeros in The Silmarillion

Score: +6

Michael Elsworth

as Cirdan in The Silmarillion

Score: -2

Timothy Spall

as Mim in The Silmarillion

Score: -1

Brendan Gleeson

as Sador in The Silmarillion

Score: +3

Derek Mears

as Gothmog in The Silmarillion

Score: +4

Dominic Cooper

as Turgon in The Silmarillion

Score: 0

Charlie Cox

as Gwindor in The Silmarillion

Score: +1

Ray Stevenson

as Finwe in The Silmarillion

Score: -2

Domhnall Gleeson

as Maedhros in The Silmarillion

Score: +6

Adewale Akinnuoye-Agbaje

as Huan in The Silmarillion

Score: +1

Helena Bonham Carter

as Ungoliant in The Silmarillion

Score: +9

Elizabeth Debicki

as Nienor in The Silmarillion

Score: 0

Iain De Caestecker

as Brandir in The Silmarillion

Score: +3

Ralph Fiennes

as Glaurung in The Silmarillion

Score: +10

Peter Facinelli

as Curufin in The Silmarillion

Score: -3

Eva Green

as Melian in The Silmarillion

Score: +17

Jack Davenport

as Fingon in The Silmarillion

Score: -1