All Cast

J.D. Daniels

J.D. Daniels

Arnold (voice)

Francesca Marie Smith

Francesca Marie Smith

Helga (voice)

Justin Shenkarow

Justin Shenkarow

Harold (voice)

Jamil Walker Smith

Jamil Walker Smith

Gerald (voice)

Craig Bartlett

Craig Bartlett

Brainy (voice)

Dan Castellaneta

Dan Castellaneta

Grandpa (voice)

Tress MacNeille

Tress MacNeille

Grandma (voice)