Matthew Broderick

John Brown / Inspector Gadget / Robo Gadget

Rupert Everett

Sanford Scolex / Dr. Claw

Joely Fisher

Brenda / Robobrenda

Michelle Trachtenberg

Penny

Andy Dick

Kramer

Cheri Oteri

Mayor Wilson

Mike Hagerty

Sikes

Dabney Coleman

Chief Quimby

D.L. Hughley

Gadgetmobile (voice)

René Auberjonois

Artemus Bradford

Frances Bay

Thelma

Mr. T

Himself

Richard Kiel

Famous Big Guy with Silver Teeth

Richard Lee-Sung

Famous Villain with Deadly Hat

Richard Penn

Fantastic Doctor

J.P. Manoux

Mayor's Sychophantic Assistant

Brian George

Sore Guru

Alexander Witt

Wet, Green Businessman

E.J. Callahan

Hot Dog Vendor

Mary Chris Wall

Snoopy News Anchor

Linda Cevallos

Showgirl

Don Adams

Brain (voice)

Danny Nero

Police Officer (uncredited)