Suggestions by @denholmhendry
166 suggestions
Robin Williams
as Dug in Up (1999)

B.O.B.
as Fictional Character played by Jack Black in The Perfect Jack Black Movie

Christian Bale
as Max in Disney's Where the Wild Things Are (1980's-1990's)
Elijah Wood
as Max in Disney's Where the Wild Things Are (1980's-1990's)

The Phantom Stranger
as Richard E. Grant in Which SUPERHEROES Could Actors Play?
Kevin Conroy
as Shadow in The Sonic Trilogy (00's).

Ted (2012)
as What If John Belushi lived? in myFiction

Robert Englund
as Scarecrow in Batman Forever (Tim Burton Version)
Liv Tyler
as Jenny Blake in The Rocketeer (2001)

Matthew Lillard
as Michaelangelo in Teenage Mutant Ninja Turtles (2001-2006)

Frank Welker
as Best Celebrity Voice Actor in Best & Worst of Cartoons
Don Messick
as Best Celebrity Voice Actor in Best & Worst of Cartoons
Christopher McDonald
as Dwayne LaFontant in Over the Hedge (1996)

Scooby Doo Where Are You?
as Blue's Clues in If this Character was in...

Michael Keaton
as Rocky Rhodes in Chicken Run (1990)
Keke Palmer
as Gloria in Madagascar

Cary Elwes
as The Flash in The JUSTICE LEAGUE OF AMERICA (1990s)
Kyle MacLachlan
as Superman in The JUSTICE LEAGUE OF AMERICA (1990s)

Phil Morris
as Martian Manhunter in The JUSTICE LEAGUE OF AMERICA (1990s)
Mara Wilson
as Madeline in Disney's Madeline (1990's)