Animation director Chuck Jones noted that while Bugs' major enemy, Yosemite Sam was loud and violent, he was obviously no threat. So, he decided to create the opposite type of character; one who was quiet and soft-spoken, but whose actions were incredibly destructive and legitimately dangerous.

Marvin the Martian made his debut in 1948's "Haredevil Hare." In his first appearance Mel Blanc gave him a stuffy, denasal voice, but later the Martian adopted a more regal-sounding, snooty, almost British phrasing.

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 "Hareway to the Stars", being freeze-dried Martians that become full-size on addition of drops of water).

Marvin wears a parody of a Roman soldier's uniform (a reference to Mars being the Roman god of war) with old-fashioned basketball shoes. His head is a black sphere with only eyes for features.

On numerous occasions Marvin has tried to destroy the Earth (it obstructs his view of Venus) with his "Uranium PU-36 Explosive Space Modulator." (The original reference to "Uranium PU-36" changed to "Illudium PU-36" in subsequent cartoons. Some people mistake the sound of "PU" for a "Q" and say "Q-36." However, the weapon's name is derived from the letters "PU" which coincidentally is the atomic symbol for Plutonium—named for the planet Pluto). Marvin is consistently foiled by Bugs Bunny. He has battled for space territory with Daffy Duck, a.k.a. Duck Dodgers in the 24½th Century.