Suggestions by @rowenjackson

Mike Myers

as Cat in the Hat in I, Looney

Rob Paulsen

as Speedy Gonzales in I, Looney

Russi Taylor

as Granny in I, Looney

Bill Farmer

as Sylvester in I, Looney

Bob Bergen

as Tweety Bird in I, Looney

John Paul Karliak

as Wile E. Coyote in I, Looney

Paul Julian

as Road Runner in I, Looney

Tress MacNeille

as Penelope Pussycat in I, Looney

Bruce Lanoil

as Pepe Le Pew in I, Looney

Kath Soucie

as Lola Bunny in I, Looney

Charles Fleischer

as Roger Rabbit in I, Looney

Kelly Sheridan

as Starlight Glimmer in I, Looney

Joe Alaskey

as Daffy Duck in I, Looney

Billy West

as Bugs Bunny in I, Looney

Robin Williams

as Thedore in I, Looney

Sam Rockwell

as Dr. Seuss in I, Looney

Ryan Lee

as Champ in I, Looney

Mick Wingert

as ACME in I, Looney

Jack Black

as RL Stine in I, Looney

Bridget Moynahan

as Calvin in I, Looney