Suggestions by @masterofcool

Dan Aykroyd

as Christopher Thorne in Valkenvania (1990)

John Lithgow

as Mr. Kub in Project X (1992)

John Franklin

as Dwarf Partygoer in Project X (1992)

Tom Hanks

as Ben Healy in Problem Child (1999)

Jack Lemmon

as Robert Newsome in Room (1990)

Gary Busey

as Nicholas Stanford in Room (1990)

Joseph Mazzello

as Jack Newsome in Room (1990)

Julia Roberts

as Joy Newsome in Room (1990)

Steven Spielberg

as Producer in Full Moon Hotel (1986)

John Landis

as Director in Full Moon Hotel (1986)

Richard Gere

as Assistant Principal Vernon in The Breakfast Club (1995)

Gene Wilder

as James Halliday / Anorak the All-Knowing in Ready Player One (1988)

Charlie Sheen

as Wade Watts / Parzival in Ready Player One (1988)

Alan Rickman

as Nolan Sorrento in Ready Player One (1993)

Julia Roberts

as Samantha Cook in Ready Player One (1993)

Chris Farley

as Kent Dorfman in Animal House (1988)

Gene Hackman

as Donald Rimgale in Backdraft (1986)

Danny DeVito

as i-R0k in Ready Player One (1993)

Charlie Sheen

as Wade Watts in Ready Player One (1993)

Gene Wilder

as James Halliday in Ready Player One (1993)