Mason Cotton as Arnold (voice)

Benjamin Flores Jr. as Gerald (voice)

Francesca Marie Smith as Helga (voice)

Anndi McAfee as Phoebe (voice)

Carlos Alazraqui as Eduardo (voice)

Alfred Molina as La Sombra (voice)

Justin Shenkarow as Harold (voice)

Antoinette Stella as Stella (voice)

Laya DeLeon Hayes as Nadine (voice)

Jamil Walker Smith as Paulo (voice)

Nika Futterman as Olga (voice)

Olivia Hack as Rhonda (voice)

Lane Toran as Che (voice)

Dan Butler as Mr. Simmons (voice)

Dan Castellaneta as Grandpa (voice)

Tress MacNeille as Grandma (voice)

Maurice LaMarche as Bob Pataki (voice)

Dom Irrera as Ernie (voice)

Kath Soucie as Miriam (voice)

Danielle Judovits as Big Patty (voice)

Danny Cooksey as Stoop Kid (voice)

Jim Belushi as Coach Wittenberg (voice)

Craig Bartlett as Miles (voice)

Gavin Lewis as Eugene (voice)

Jet Jurgensmeyer as Stinky (voice)

Aiden Lewandowski as Sid (voice)

Nicolas Cantu as Curly (voice)

Wally Wingert as Oskar (voice)

Stephen Stanton as Pigeon Man (voice)