Marvin hails from the planet Mars, but is often found elsewhere. He is often accompanied by his dog "K-9", and sometimes by other creatures (one gag, first used in Hare-Way to the Stars (1958), being candy-sized "Instant Martians" that become full-size on addition of drops of water).
Marvin wears a Roman soldier's uniform, with basketball shoes. The style of these shoes resembles the Chuck Taylor All-Stars brand name, considered to be the "generic" or "standard" basketball sneaker. His head is a black sphere with only eyes for features. The curved crest of his helmet appears, with the push-broom-like upper section, to comically resemble an ancient Greek hoplite's or a Roman centurion's helmet. The appearance of the combination of Marvin's head and helmet allegedly led to Bugs Bunny thinking he was a "bowling ball wearing a spittoon" in one short. Marvin speaks with a soft, nasally accent, and often speaks technobabble. The helmet and skirt that surround him are green and his suit is red (in a few of the original shorts, his suit was green). He is also known for his trademark quotes "Where's the kaboom? There was supposed to be an Earth-shattering kaboom!", "Isn't that lovely?", and "This makes me very angry, very angry indeed."
Marvin the Martian can be seen wandering around OASIS.