The First Meet-Up
Teenage Mutant Ninja Turtles first meet Nobody when they are hanging around in Springfield after they have gotten bored watching TV. When they meet, Nobody is been shot and asks Turtles to help him by following a truck. The Turtles are suspicious about nobody, but agree to help him after seeing his badge (he is a cop). Nobody is investigating peculiar activities of a new salvage company. It turns out that the new salvage company is selling left over arms of a company called Rufington Arms. Ruffington Arms is a gun manufacturer, who manufactures guns for the government. With the help of Turtles, Nobody is able to stop arm dealing and arrest bad guys.
Casey Jones: Killer
When Casey Jones accidentally kills a teenager, Nobody is there to guide Casey back from the brink of violence and alcohol he had pushed himself to.
The turtles travel to the desert after Raphael had been kidnapped, and, along with Mr. Braunze, Nobody follows. He seemingly sacrifices himself and is apparently killed when trying to fight off a giant, tentacled monster.
After April goes through her nanobot ordeal, she undergoes a personal journey that eventually leads her to don an all black costume and garner the title of "Nobody." After hearing rumors of signifying Nobody's return, Casey Jones investigates only to find the aloof April.
Nobody is apparently resurrected a decent amount of time later. However, this does not seem to be the same nobody as the one before. It is explained that he was healed but, with an entity given to him, is now a supernatural crime fighter. In this incarnation, he wears a glowing white costume instead of black.