Marvin the Martian first debuted in the episode, Members Only, where he sang his own Merrie Melodie about how being another planet inhabitant is hard because people will think you are a misfit called I'm a Martian. In the song, Marvin wants to be friends with everyone and says he's a nice guy. However, when someone makes fun of his awkward-looking helmet, he gets angered. He then sings about his plan to fulfill destroying Earth and is seen moving his laser to destroy Earth. This was also the first appearance of Marvin's martian dog, K-9, who was seen in Marvin's lab with dog parts, after Marvin mentioned he makes puppies in his lab; and the Instant Martians, who help him with the party.
In Reunion, Marvin appears in a flashback going to Daffy's high school. He is shown to not have had his helmet, due to having a long, thick line of blonde hair sticking out of the top of his head. He is shown to have been friends with Pete Puma and still is in the present. It may also be noted that he had a dislike of Daffy because when Daffy said he wanted to sit with Pete and Marvin, they both had moved away. In the present time, Marvin was seen at the reunion along with Pete, and tells Daffy and Pete that he has been plotting to destroy earth due to high school being a hard time for him. He seems to still hold an unreasoned grudge against Daffy (if he ever did) due to yelling at Daffy when he tells him that he was a player for a famous football team, while he had told another person at the reunion that he had been the coach of the team. He also appeared briefly in the Merrie Melodie, Cock of the Walk, where he is seen inside a UFO that Foghorn Leghorn is laying and singing on, because he caught them.
Marvin then appears in Sunday Night Slice, where he works for Bugs' new pizza restaurant as a cook. He is later seen locked into a closet by Bugs and Speedy along with Daffy and Pete after being considered "bad service". He is later seen at the end of the episode working as a delivery man for Speedy at Pizzariba along with Daffy and Pete.