Me-Mow is an assassin that appeared as a major character in the episode "Jake vs. Me-Mow." Pendleton Ward has confirmed that Me-Mow is a fan-made character, and is included in the show because "it's so cute and it was drawn by a tiny kid." She is a second-class assassin of the Guild of Assassins and is trying to kill Wildberry Princess to become a full-member assassin. A note was stabbed to Wildberry Princess' doorman, which said, "we are going to assassinate you." During the episode, Me-Mow poisons Jake with a syringe full of green liquid that is capable of killing a dog fifty times the size of Jake. Jake grows his liver to fifty-one times the size of an average dog, stopping the poison. Me-Mow stated when she failed her assassin's test that she would have to wait a year to retake it. Infuriated, Me-Mow responds by leaping at the princess to kill her, but at the last moment, the princess pops her berries and Me-Mow soars off the cliff. Me-Mow surviving from the fall by flying away on the back of a blue bird.
Me-Mow reappeared in "Angel Face," now having grown to the size of an average adult human. She has since been kicked out of Guild of Assassins, likely for her failure, and become a bounty hunter. She manages to capture Finn, who was mistaken for having a bounty on his head due to the wanted posters BMO had made for his roleplaying event and is later confronted by Jake and BMO, who capture and imprison her in the Candy Kingdom Dungeons.
Me-Mow is a tiny white cat with cream/tan colored striped fur. She has large pink eyes, a lamprey-like mouth with pointed teeth, and razor sharp claws. Her tail is unusually long and prehensile, and she used it to carry a test tube of red liquid, which is an antidote to her poison. Her tail can puff up during attack mode. She carries a syringe, that has a picture of her face on it, filled with green poison. She keeps a dagger in her mouth or throat.
Besides her skills with stealth, as well as having a hidden dagger inside her mouth, she is extremely agile - able to jump great heights and scale objects with ease. She is also skilled in concealing herself and is capable of climbing sideways on surfaces.
- Me-Mow did not have a tail in the original drawing.
- The fan who created Me-Mow is named Gunnar Gilmore.
- As with most characters of unusual sizes, Me-Mow's size varies throughout the episode. Her size varies from being as big as Finn's hand to small enough to fit in Jake's nose with plenty of extra space.
- Her name may be a play in "meow" the onomatopoeia of cat, "mow" that is a synonym of "reap" or from the Portuguese word "mau" that means "evil" or "bad."
- Me-Mow's mouth, when she is in attack position, is round and resembles that of a lamprey.
- Me-Mow appeared as "Mow-Me" in the Adventure Time comic, Issue 5, where she appears on Adventure Tim's chart labeled as Lawfully Evil.
- Me-Mow is female but male in the Latin American and European Portuguese dubbing.
- In the official Adventure Time Encyclopædia, Hunson Abadeer breaks the fourth wall by stating, "On an artistic level, Me-Mow's appearance seems primitive, almost as if a child designed her. But I digress." This is probably a reference to the fact that she's a fan-made character.
- Me-Mow looks similar to Kira Yoshikage's stand "Killer Queen" from the anime and manga series, JoJo's Bizarre Adventure. 
Names in other languages
- Her Italian name is Gattivo
- Her Polish name is Miau Miau
- Her Turkish name is Mi Yav