|Species||Dog (Now roboticised)|
|First Appearance||Heads or Tails|
Sometime prior to the start of the series Muttski, along with Uncle Chuck, was captured and roboticised by Dr. Robotnik and turned into the robot dog he is now. During the episode Heads or Tails Sonic and Tails had gone to Robotropolis to search for cotter pins when they ran into Muttski whilst he was patrolling, but due to his roboticisation Muttski attacked them both. Sonic managed to duck out of the way of Muttski's bites and scolded him for misbehaving. During that moment when Sonic told Muttski to sit and stay he temporarily broke his programming and regained his friendly personality. Sonic asked Muttski if he had seen Uncle Chuck recently, but Muttski just shook his head. Moments later, the reprogramming took over again.