Ben Diskin as Nigel 'Numbuh 1' Uno / Hoagie Pennywhistle 'Numbuh 2' Gilligan Jr / Numbuh 101 (voice)

Lauren Tom as Kuki 'Numbuh 3' Sanban (voice)

Dee Bradley Baker as Wally 'Numbuh 4' Beatles / Mr. Fibb / Toilenator / Joaquin / Tommy Gilligan (voice)

Cree Summer as Abigail 'Numbuh 5' Lincoln / Former Numbuh 11 - Cree Lincoln (voice)

Jason Harris as Chad Dickson (voice)

Grey DeLisle as Crazy Old Cat Lady/Gramma Stuffum (voice)

Jeff Bennett as Mr. Boss / Mr. Fizz / Benedict Wigglestein (voice)

Jennifer Hale as Fanny 'Numbuh 86' Fulbright / Computer (voice)

Mark Hamill as Stickybeard (voice)

Tom Kenny as Knightbrace / Mr. Wink (voice)

Maurice LaMarche as Father (voice)

Matt Levin as Patton 'Numbuh 60' Drilovsky (voice)

Frank Welker as Monty Uno (voice)

Neil Ross as Grandfather (voice)

Daran Norris as Count Spankulot (voice)

Rachael MacFarlane as Rachael T. 'Numbuh 362' McKenzie (voice)

Ogie Banks as Sector Z Numbuh 0.1 - Bruce (voice)

Janice Kawaye as Sonya - Number 83 / Lee - Numbuh 84 (voice)

Dave Wittenberg as Numbuh Zero / Lenny - Sector Z Numbuh 0.4 (voice)

Cam Clarke as Additional Voices (voice)

Candi Milo as Additional Voices (voice)