Arnold

J.D. Daniels

as

Arnold (voice)

Francesca Mari...

as

Helga (voice)

Justin Shenkar...

as

Harold (voice)

Jamil Walker S...

as

Gerald (voice)

Craig Bartlett

as

Brainy (voice)

Dan Castellane...

as

Grandpa (voice)

Tress MacNeille

as

Grandma (voice)