Robin Williams ... Rainbow Randolph
Edward Norton ... Sheldon Mopes / Smoochy the Rhino
Catherine Keener ... Nora Wells
Danny DeVito ... Burke Bennett
Jon Stewart ... Marion Frank Stokes
Pam Ferris ... Tommy Cotter
Danny Woodburn ... Angelo Pike
Michael Rispoli ... Spinner Dunn
Harvey Fierstein ... Merv Green
Vincent Schiavelli ... Buggy Ding Dong
Craig Eldridge ... Husband
Judy White ... Wife
Tim MacMenamin ... Danny
Bruce McFee ... Roy
Glen Cross ... Jimmy
Bill Lake ... Bartender
Nick Taylor ... Henry the Thug
Richard Cocchiaro ... Mitch the Thug (as Richard A. Cocchiaro Jr.)
Tracey Walter ... Ben Franks
Louis Giambalvo ... Sonny Gordon
Colin Moult ... Rhinette / Krinkle Kid #1
Nikolai Tichtchenko ... Rhinette / Krinkle Kid #2
Martin Klebba ... Rhinette / Krinkle Kid #3
Tonya Renee Banks ... Rhinette / Krinkle Kid #4
Christy McGinity ... Rhinette / Krinkle Kid #5 (as Christy Artran)
Philip Craig ... Senator
Natasha Kinne ... Smoochy's Secretary
Richard Hamilton ... Old Vagrant
Shawn Byfield ... Rickets
Todd Graff ... Skip Kleinman
Melissa DiMarco ... Tara
Dan Duran ... Hunter
Michael Copeman ... Reporter #1
James Carroll ... Reporter #2
Phillip Jarrett ... Reporter #3 (as Philip Jarrett)
Suzanne Leonard Feliz ... Reporter #4
Thomas Lyons ... Reporter #5
Angela Bullock ... Reporter #6
Robert M. Sussman ... Reporter #7
George Blumenthal ... Reporter #8
Matthew Arkin ... Save the Rhino Man
Hugo Jansuzian ... Hispanic Dad
Silvia Rojas ... Hispanic Mom
Mario Andres Torres ... Hispanic Boy
Sabrina Jansuzian ... Hispanic Girl
John 'Cha Cha' Ciarcia ... Autograph Man
Fred Scialla ... Man in Crowd (as Fred Peter Scialla)
Adam Bryant ... Man in Crowd #2
Richard Ziman ... Man in Crowd #3
Frank Anello ... NYPD
Samantha Cordero ... Little Girl
Peter Keleghan ... News Anchor
Rothaford Gray ... Ellis
David Lawrence Brown ... McCall (as Dave Brown)
Gerry Quigley ... Ian
James Binkley ... Cop #1
Dylan Roberts ... Stagehand
Vito Rezza ... Lead Cop
Lou Cantres ... Little Girl's Dad
John Cleland ... John
Lauren Flanigan ... Opera Diva
Cara Wakelin ... Princess
Ted Kavouris ... Candy Seller
Tony Ashmore ... New Yorker on the Street (uncredited)
Ty Copeman ... Car and Driver (uncredited)
Antonio Cordero ... Rainbow Randolph Friend (uncredited)
Jonah Falcon ... Man (uncredited)
Frank Falcone ... Man in crowd (uncredited)
Katie Finneran ... Woman in Crowd (uncredited)
Edie Inksetter ... Molly (uncredited)
Greg Korin ... Smoochy Fan (uncredited)
Peter Kosaka ... Takeshi Yamashita (uncredited)
Danny LeGare ... Newsstand Clerk (uncredited)
Richard D. Leko ... Smoochy Land Band Member (Purple & White Monkey Keyboard Player) (uncredited)
Peter Loung ... Blue (uncredited)
Robert Mauzell ... Security Guard at methadone clinic (uncredited)
Felicia Peluso ... Woman in park with baby carriage; watching Robin Williams dance (uncredited)
Martin Pfefferkorn ... Meth Addict at Clinic (uncredited)
Robert Prosky ... Network Chairman (uncredited)
Michael Sercerchi ... Michael (uncredited)
Marc Yarrish ... Street Vendor (uncredited)