Marty is a Thwomp found behind jail bars in Mario Kart 64's Bowser's Castle. He is laughing and looks at you through the bars. He appears in the first room of the castle, the jail bars being in front of the first turn into the corridor into the next room. The lighting in the cell makes him appear green, he is also found in Mario Kart Wii although the lighting has been removed.
- There are also rumors that say you can unlock him in Mario Kart 64, which are not true.