Suggestions by @skytalk

Harmony Korine

as Director in Pig (2001)

Dennis Hopper

as Darius in Pig (2001)

Werner Herzog

as Audiobook Narrator in Pig (2011)

Rutger Hauer

as Robin "Rob" Feld in Pig (2001)

James Franco

as Amir in Pig (2001)

Robert Crumb

as Carl in A Different Man (1984)

Damien Bonnard

as Umar in Limbus Company (Live Action Television Series)

Lee Sung Jin

as Executive Producer in Limbus Company (Live Action Television Series)

Vangelis

as Composer in Uncut Gems (1999)

Björk

as KG's Agent in Uncut Gems (1999)

Vincent Gallo

as Mohegan Sun Gambler in Uncut Gems (1999)

Ryan Phillippe

as Norwegian Boy in Uncut Gems (1999)

George Gervin

as Glenn 'Doc' Rivers in Uncut Gems (1999)

David Mamet

as Man on Street in Uncut Gems (1999)

Robin Wright

as Lexis in Uncut Gems (1999)

Melanie Griffith

as Boston Player Personnel in Uncut Gems (1999)

Julie Christie

as Anne - Adley's Auction Manager in Uncut Gems (1999)

RZA

as Trinidad James in Uncut Gems (1999)

Will Smith

as Ca$h Out in Uncut Gems (1999)

James Earl Jones

as Howard's neighbor in Uncut Gems (1999)