Carter is a young man who became an ally of the Teenage Mutant Ninja Turtles during the two final seasons of the 1987 TV series. He was introduced in the first episode of Season 9. "The Unknown Ninja", as he studied martial arts under Master Splinter. At first, the TMNT disliked him because he always wanted to do things his own way, but later they finally see him as a team member. After exposure to a sample of the Turtles' mutagen, he gained the ability to change into a large yellow mutant with great strength. After the turtles found out a short while later, Carter became a part of the team for the remainder of Season 9 and the first half of Season 10. The Turtles have since then worked to find a cure for Carter's mutation. Carter drove a motorcycle and often accompanied the TurtleVan.
After choosing to return to his previous college life in Season 10, Donatello stabilized Carter's mutation, but on his way out of the city, Carter learned from April O'Neil that she and the Turtles were captured by Lord Dregg, Krang, and the Shredder. After the events in "Turtles to the Second Power", Carter decided to travel to the future with the turtles' friends Landor and Merrick seeing it as the only way to be fully cured of his mutation.