Justin Long as Humphrey (voice)

Hayden Panettiere as Kate (voice)

Dennis Hopper as Tony (voice)

Danny Glover as Winston (voice)

Larry Miller as Marcel (voice)

Eric Price as Paddy / Mooch (voice)

Vicki Lewis as Eve (voice)

Chris Carmack as Garth (voice)

Kevin Sussman as Shakey (voice)

Brian Donovan as Salty (voice)

Christina Ricci as Lilly (voice)

Elizabeth Tulloch as Sweets (voice)

Christine Lakin as Reba (voice)

Mindy Sterling as Debbie (voice)

Fred Tatasciore as Garn (voice)

Nika Futterman as Porcupine (voice)

Mela Lee as Candy (voice)

Steve Vinovich as Park Ranger (voice)

Aziz Ansari as Thug (voice) (uncredited)

Eric Lopez as Can-do (voice)

Marilyn Tokuda as Claws / Janice (voice)

Maya Kay as Bear Cub (voice) (as Maya Feltheimer)