Some TMNT stuff really isn't for little kids.
Edward Nygma is the criminal known as The Riddler, who is obsessed with leaving clues to his crimes in the form of riddles.
The Riddler was one of several super villain inmates incarcerated in Gotham's infamous Arkham Asylum who was exposed to mutagen as part of a plot by the Shredder and Ra's al Ghul to take control of the city with a mutant army. Riddler was mutated into a raccoon, increasing his agility and reflexes as well as gifting him with the animal's natural climbing abilities.
During the final battle, he was among the combatants whom Splinter fought, and was defeated. It was later confirmed that he would revert back to normal in a week's time.
- With his trademark question mark cane and new mutant form, the Riddler resembles Sly Cooper, Sucker Punch studios' anthropomorphic video game thief.