Atomic Lass is a popular fictional character in Rise of the Teenage Mutant Ninja Turtles, from the Jupiter Jim Extended Universe, and was Donatello's childhood idol and crush. Atomic Lass first appeared in Mascot Melee as the mascot guise of the otherwise unnamed leader of a gang of mutant cockroach thieves.
The thief first made her appearance in Times Square in the guise of a bald man with a long, red beard. She stole Raphael's wallet, and later appeared in her Atomic Lass costume, where she was angered at having been shown up by Raphael, who had become a source of attention due to April O'Neil's "Turtlepotamus" meme.
Atomic Lass and her crew started a dance-off/fight against the Ninja Turtles and Donatello danced with her, and also fought her reluctantly. Upon knocking off her mascot "head", it was then revealed to the Turtles that she was the red-bearded man, and then after the true forms of her companions was revealed, she too, was revealed to be a mutant cockroach. Donatello defeated Atomic Lass while his brothers handled her crew.
- The face of Atomic Lass's human disguise bears a resemblance to series creator and executive producer Ant Ward.