Suggestions by @shrimpy

Willem Dafoe

as Robert House in Fallout: New Vegas

Score: +6

Seth MacFarlane

as Courier's brain (Voice Only) in Fallout: New Vegas

Score: +2

Scott Eastwood

as The Lonesome Drifter in Fallout: New Vegas

Score: 0

Danny Glover

as Dennis Crocker in Fallout: New Vegas

Score: 0

Wayne Newton

as Mr. New Vegas (Voice Only) in Fallout: New Vegas

Score: +2

Gary Oldman

as Joshua Graham in Fallout: New Vegas

Score: 0