Marty The Thwomp

Marty the Thwomp is a green Thwomp that appears in Bowser's Castle in Mario Kart 64, nicknamed Marty by the community. They are found in a prison cell in the race track and cannot be interacted with. Why they were locked up is unknown.

However, there are theories that Marty the Thwomp can be unlocked as a playable driver, the most popular methods seemingly being in this video and this video, which turned out to be April Fools rumors. However, it is possible that Marty the Thwomp has been created by the Personalization A.I. after it was injected into Mario Kart 64.

Marty the Thwomp can manifest in Super Mario 64 as well, usually after the Personalization A.I. is injected into the Mario Kart 64, but can appear without it. It is a simple reskin of a Thwomp, making it a green. It mostly acts the same as a regular Thwomp, but has been documented to have new behaviors.

Trivia

 * Marty the Thwomp is not actually green, it just appears so due to the yellow lighting in the room they are found in.