Suggestions by @nolanmassey

Martin Short

as Petrie in The Land Before Time

Ida Lupino

as Writer in Doctor Who: Season 4 (1966 American Version)

Richard Donner

as Writer in Doctor Who: Season 4 (1966 American Version)

Roger Corman

as Producer in Doctor Who: Season 4 (1966 American Version)

Boris Karloff

as The Toymaker in Doctor Who: Season 3 (1965 American Version)

Willem Dafoe

as The Master in What If Doctor Who Wasn't Axed? Season 37 (2000) (American Version)

Ed Wynn

as Cyril in Doctor Who: Season 3 (1965 American Version)

Sterling Holloway

as The Doctor in Doctor Who: Season 5 (1967 American Version)

Robin Williams

as 5th Doctor in Doctor Who American

Hayden Christensen

as The Flash in DC Extended Universe (2003-2013)

Hugh Grant

as Vector Perkins in Despicable Me (2000)

John Cleese

as Dr. Nefario in Despicable Me (2000)

Ben Stiller

as Gru in Despicable Me (2000)

Steve Buscemi

as Gru in Despicable Me (2000)

Darren McGavin

as The Second Doctor in Doctor Who: Season 4 (1966 American Version)

Don Knotts

as The Second Doctor in Doctor Who: Season 4 (1966 American Version)

Dick Van Dyke

as The Second Doctor in Doctor Who: Season 4 (1966 American Version)

Sterling Holloway

as The Second Doctor in Doctor Who: Season 4 (1966 American Version)

Joseph Stefano

as Writer in Doctor Who: Season 4 (1966 American Version)

Burgess Meredith

as The Doctor in Doctor Who: Season 4 (1966 American Version)