Robot/Marf

Curtis Armstrong

Monster

Harland Williams

Gart / Perry / Loudmouth (voice)

Maurice LaMarche

JD

Megan Hilty

Ogo

Jonathan Slavin

Spitfire / Globitha (voice)

Cree Summer

Guest Voice

Leon Thomas III

Hal Worth-a-ton / Uncle Kuffley / Crikey (voice)

Nolan North

Punch Morley (voice)

Fred Tatasciore

Lucy (voice)

Jennifer Cody

Nessie (voice)

Rhea Perlman

Mr. Wheelie (voice)

Kurtwood Smith

Katie

Carol Ann Susi

Voice

Julianne Buescher

Master Grabmirist (voice)

Ping Wu

Snap Winsome / Lil' Lugnuts (voice) / Snap Winsome (voice)

Jeff Bennett

Arpa / Grandma 10010 (voice)

April Winchell

Crazy Cousin Gizmo (voice)

Alan Tudyk

Lev (voice)

Bill Fagerbakke

Dame Lady Madame (voice)

Ruth Williamson

Sir Cranklin (voice)

Jon Polito

Bob / Scale (voice)

Rob Paulsen

St. Crispy (voice)

Jeffrey Tambor