Suggestions by @bradleysigma

Anthony Stewart Head

as Ozpin in RWBY

Score: -4

Anna Kendrick

as Nora Valkyrie in RWBY

Score: -5

Diana Rigg

as Mrs. Peacock in Clue

Score: -4

Nathan Fillion

as Colonel Mustard in Clue

Score: -4

David Mitchell

as Professor Plum in Clue

Score: -3

Adam Scott

as Mr. Green in Clue

Score: +9

Rowan Atkinson

as The Bursar in Discworld

Score: +15

Stephen Fry

as The Dean in Discworld

Score: +11

Hugh Laurie

as Mustrum Ridcully in Discworld

Score: -2

Jonathan Banks

as "Mac" McAnally in The Dresden Files

Score: +22

Fran Kranz

as Hades in The Dresden Files

Score: -8

Jonathan Pryce

as Father Forthill in The Dresden Files

Score: +24

Gwendoline Christie

as Sigrun in The Dresden Files

Score: +3

Sean Maher

as Mortimer Lindquist in The Dresden Files

Score: -10

Enrico Colantoni

as Uriel in The Dresden Files

Score: -7

Evanna Lynch

as Murphy in The Dresden Files

Score: -23

Crispin Glover

as Nicodemus in The Dresden Files

Score: -3

Zach Woods

as Binder in The Dresden Files

Score: -15

Iain Glen

as Michael Carpenter in The Dresden Files

Score: -20

Jerome Flynn

as Jared Kincaid in The Dresden Files

Score: -17