When April and Casey found a stray cat, Mikey took care of her, but after she ate some of Mikey's spilled ice cream that was mixed with mutagen she transformed into a mutated ice cream cat hybrid. Ever since then she's lived in the freezer in the Kitchen Lair, then in the freezer in the O' Neil farmhouse. She is affectionate and cuddly.
She's composed of three prominent flavors: a tiny dab of chocolate, vanilla (which makes up her whole torso) and strawberry that makes up her upper body, but before she got mutated, she was a wounded brown-striped street cat that had appearances in both the foreground and background in several prior episodes. She currently lives in the Turtles' freezer and Mikey uses a portable cooler to carry her around when venturing outside if necessary.
Originally just a normal feline, when the cat consumed mutagen-tainted ice cream, it turned into an amorphous ice cream monster.
Her body is composed of Neapolitan Ice Cream, with the head being strawberry, the torso made of vanilla and the waist and lower body made of chocolate with short stubby arms made of chocolate and vanilla. Her tail is made out of vanilla and chocolate also.
In "Of Rats and Men", Ice Cream Kitty made her first appearance as a normal cat pouncing on a rat. April saw her and took pity on her, and decided to take her back to the lair. April dropped off Kitty at Donnie's lab, where Mikey was eating ice cream. After Mikey left April's kitty unattended next to a mutagen recipient, where his ice cream fell earlier, the cat licked it and then ice cream kitty was born. Horrified at what had happened and afraid of what could happen to him if caught, Mikey quickly hide Ice Cream Kitty in the Turtle's Freezer. Later, Mikey took Ice Cream Kitty in a cooler and flung her into the Rat King, where she attempted to scratch him.
In "Pizza Face", Ice Cream Kitty is shown, still residing in the Turtles' freezer. After Mikey had finished interrogating one of Pizza Face's goons, he threw it in the freezer with Ice Cream Kitty who instantly horrified the defenseless pizza goon with her unsettling head turn.
In "The Invasion Part 2", Mikey packs her up in a portable freezer to take her with him as they try to find a new lair.
In "A Foot Too Big", when Bigfoot opened the fridge ice cream kitty was freaked out by Bigfoot and vice versa and the two continued to scream until Bigfoot threw out the fridge.
In "Buried Secrets", it shows she actually understands Michelangelo suspecting April's mom as a fake. While listening to him, Mikey sprays some whipped cream on her head and placing a cherry on top. Ice Cream Kitty then senses something and begins to hiss furiously, revealing April's mom with a canister of mutagen. She lets Mikey go after her.
In "The Croaking", she is seen playing around with Mikey as they watch their favorite show Crognard The Barbarian; while destroying the living room in the process. After the others come in and scold at him, he packs up and leaves. He then says goodbye to her and promises that April will take care of her.
In "Return to New York", She is in the cooler and is happy after Mikey tells her that their going home to New York City as they pack up and leave the old farmhouse.
In "Battle for New York, Part 1", She (alongside Mikey who are both wearing lab jackets and goggles) are seen experimenting with mutagen and other ingredients only to create more Retro-Mutagen which surprises them all (especially Donnie), who comes in and begins to fight and argue with him for doing such.
In "The Creeping Doom", she is seen giving April a ice-pack for Donnie who's acting weird. April the talks to Splinter who offers her some wisdom. He then asks her to close the fridge for Ice-Cream Kitty will melt.
In "The Fourfold Trap", Ice Cream Kitty shows impressive skills at card-playing, defeating Mikey with ease. Her meows are given insulting subtitles as she shows her winning hand.
In "Broken Foot", she plays the Mazes and Mutants game with Donnie, Mikey, Raph and April in the beginning of the episode.
In "Bat in the Belfry", she sits by Mikey as he reads his Wingnut comics.
In Owari, Ice Cream Kitty was among the mourners at Splinter's funeral.
- She is voiced by Kevin Eastman, the co-creator of the Teenage Mutant Ninja Turtles.
- According to Kevin Eastman Ice Cream Kitty is based on Klunk.