Mouser is a large, anthropomorphic mouse who wears sunglasses that cover his eyes, along with red gloves and boots. He has a Swiss accent, saying "zat" instead of "that", and having a love of Swiss cheese. Mouser is very prideful and doesn't think of himself as an ordinary mouse, though he still gets afraid when Bowser threatens or gets angry with him. He is second-in-command and likes to utilize bombs as his primary form of attack.