• 
  Harland Williams

  Monster
• 
  Maurice LaMarche

  Gart
• 
  Curtis Armstrong

  Robot
• 
  Nolan North

  Crikey
• 
  Rhea Perlman

   Nessie (12 episodes, 2012-2013)
• 
  Jonathan Slavin

  Ogo
• 
  Cree Summer

   Spitfire / ... (15 episodes, 2012-2013)
• 
  Fred Tatasciore

  Punch Morley

• 
  Megan Hilty

   J.D. (12 episodes, 2012-2013)
• 
  Ping Wu

  Master Grabmirist
• 
  Jeff Bennett

  Snap Winsome
• 
  April Winchell

  Arpa
• 
  Julianne Buescher

  Tube Voice
• 
  Jennifer Cody

  Lucy
• 
  Kurtwood Smith

  Mr. Wheelie

• 
  Bill Fagerbakke

  Lev
• 
  Leon Thomas III

  Monster
• 
  Kari Wahlgren

  Robo Ono
• 
  Jeffrey Tambor

  Saint Crispy