Suggestions by @paulmantell

Don Marion Davis

as Count Nightwing in Goosebumps: The Movie (1998)

Score: +2

Larry Storch

as The Haunted Mask in Goosebumps: The Movie (1998)

Score: +2

Mike Maronna

as Alex in Goosebumps: The Movie (1998)

Score: +2

Lalo Schifrin

as Composer in Robert Altman's Shrek (1981)

Score: +2

Jules Feiffer

as Writer in Robert Altman's Shrek (1981)

Score: +1

Robert Altman

as Director in Robert Altman's Shrek (1981)

Score: +1

Peter Sellers

as Lord Farquaad in Robert Altman's Shrek (1981)

Score: 0

Walter Williams

as Gingy (voice) in Robert Altman's Shrek (1981)

Score: +1

Scatman Crothers

as Donkey (voice) in Robert Altman's Shrek (1981)

Score: +3

Madeline Kahn

as Princess Fiona in Robert Altman's Shrek (1981)

Score: +1

John Belushi

as Shrek (character) in Robert Altman's Shrek (1981)

Score: +3