As a normal baby alligator, Leatherhead was raised by a kind human boy (whose name remains unknown) until his disapproving parents flushed him down the toilet into the sewers. This is where the Kraang found him and brought him back to their dimension. They performed horrifying experiments on him but, through all of it, they could not break his spirit. He escaped his captivity and returned to Earth using the Kraang's dimensional portal, at the same time stealing the Power Cell that ran it. Without this cell the Kraang cannot pass between Earth's dimension and their own. The Kraang had been hunting Leatherhead and the power cell for six months when the turtles found him.
It Came From The Depths: The turtles find Leatherhead in pitched battle with a squad of Kraang. Michelangelo leads the charge to help him. Leatherhead is rendered unconscious and Mikey convinces the others to take him back to the lair. Leatherhead attacks the turtles repeatedly but Mikey is able to befriend him and earn his trust. When the other turtles recover the power cell and Leatherhead sees what they have done he loses control again and attacks all of the turtles, even Mikey. Splinter is able to defeat him and drive him off. Mikey immediately rushes out to find him. He finds Leatherhead at his own lair in an abandoned subway car. The other turtles arrive, thinking Leatherhead will hurt Mikey but Leatherhead pleads with them and explains his origins. He then entrusts the power cell to Mikey, his first friend, and goes out to fight the attacking Kraang and give the turtles time to escape. He destroys all of the Kraang in order to keep the fact that the turtles possess the power cell a secret.
TCRI : Leatherhead is awoken to grab Donnie in the face again. He snaps out of it and tells the gang all he remembers about the Kraang and the portal. He is used as a distraction to allow the gang to get to the top of the TCRI building. He beats up Traag and goes through the portal to give the turtles time to escape. He is now traped in Dimension X. It is unknown if he will return.
Leatherhead is a mutated alligator. He resembles a gator (or more accurately a crocodile) with humanoid arms, legs, and the ability to speak and reason. He is immensely large, has a long tail, sharp claws, and large mouth like all alligators do. He has a tough, armored hide is extremely resistant to attacks, even from Kraang laser blasts.
He possesses a third eyelid, which all alligators have so that they can see underwater. This third lid locks in place whenever Leatherhead goes into a rage.
Like the majority of the mutants, Leatherhead has the abilities to speak and reason. He's immensely large and powerful using his tail, claws, and crushing bite to full effect in combat. His tough, armored hide is extremely resistant to attacks, even from Kraang laser blasts.
Leatherhead is very intelligent, as it seems his time with the Kraang enabled him to gain knowledge and learn what he can about them. Despite his long snout, he is actually able to speak quite eloquently, though his voice is very deep and gravelly. He seems to have an unbreakable amount of willpower, as he would never give into the Kraang no matter what they did. Like Raph, Leatherhead has a high temper which can be used to make him stronger, in the right way, but it can leave devastating results as it causes him to go into an uncontrollable amount of rage, endangering anyone, even those he cares about...
He possesses a third eyelid, called a nictating membrane, which all alligators and relatives have so that they can see underwater. This third lid locks in place whenever Leatherhead goes into a rage. He also uses a typical alligator move in combat; the Death Roll. Leatherhead rolls along the ground, crushing opponents with his weight and sharp back plates.
Despite his monstrous form and appearance, Leatherhead has a surprisingly gentle soul and doesn't really wish to hurt anyone. He suffers from severe self-loathing from a life of horrific abuse and everybody around him fears him as a monster. He also has periodic bouts of rage in which he can lose complete control of himself. When he awakens later, he is always contrite and regretful for the things he has done. Because of his horrific treatment by them, he has an everlasting hatred for the Kraang and simply hearing the word "Kraang" will throw him into a rage.
So far, only Mikey has been able to calm him from these rages. Leatherhead has established a lair for himself in an abandoned subway car, where he keeps his few belongings; a stuffed alligator, a record player with an old jazz record that he uses to calm his rage, and the Kraang power cell which he guards with his own life. He has proven to be a very strong ally to the Turtles, even saving them from Traag by throwing the rock monster and himself into the portal to Dimension X. This brave alligator's fate remains unknown.
The Kraang: Leatherhead has an endless amount of hatred for the Kraang for all the things they done to him. While they did take him in when he was a baby, they subjected him to several experiments which continuously haunt and torture Leatherhead to this day. Even hearing the word "Kraang" makes him go insane. The abuse he suffered from them caused him to go into uncontrollable rages especially when he has nightmares. He's determined to destroy them once and for all.
All Of The Turtles: The Turtles (mainly Mikey) rescued Leatherhead when he was being chased by the Kraang. At first, excluding Mikey, they were wary about him because of his temper and size, but none the less, they see him as a valuable ally. Leatherhead see's them all as his only true friends that he can trust, and slowly starts opening up to them.
Donatello: Donnie has neutral feelings about Leatherhead. While he sees him as a valuable ally, Donnie's very terrified of Leatherhead; mostly because there's a running gag where whenever Leatherhead loses control, he grabs Donnie by the face and shakes him like a rag doll. Leatherhead has regretted this action though and he sees Donnie as a good friend, like he does all the Turtles.
Michelangelo: Out of all the Turtles, Leatherhead and Michelangelo have the closet friendship. Mikey was the first out of all his brothers to be willing to rescue Leatherhead from the Kraang. Despite his brothers' fears and warning that it wouldn't be a good idea, considering the mutant alligator had a temper, Mikey managed to convince them to bring him back to the lair. While the other turtles went to look for the powercell, Mikey took the time to befriend Leatherhead. Leatherhead really opened up to Michelangelo and really liked how he gave him his name and his pizza noddle soup. Mikey went after Leatherhead when he went on a rampage and attacked his family, when Donnie showed the powercell to Leatherhead. When the Kraang attacked, Leatherhead handed the powercell to Mikey and his brothers and fought the Kraang so they could escape, because since the youngest turtle trusted him, he decided to trust him. Mikey is the only one of the Turtles who can calm down Leatherhead when he goes berserk. Leatherhead participated in helping the Turtles in TCRI, where he sacrificed himself so the turtles could escape. Mikey was the saddest of them all to see his friend go. The bond that the two formed helped Leatherhead learn to trust people, and made him want to defeat the Kraang even more.
- Leatherhead was the first mutant turned in the Kraang's world.
- Like his 2003 incarnation, he is an ally of the turtles.
- Most likely Leatherhead had a run in with Traag during his past in Dimension X.
- He is close friends with Mikey.
- Leatherhead has a deep scar on his left pectoral muscle from when he escaped from The Kraang.
- Every time Leatherhead loses control of his anger around the Turtles, he likes to grab Donnie by the face and pretty much shake him like a rag doll.
- He is one of a few mutants that was not human when mutated.
- When he is angry, Leatherhead's eyes are covered with white membranes that are naturally used as a third eylid to see underwater for alligators and crocodiles.
- So far, Mikey is the only Turtle whom Leatherhead addresses by name.
- In season two Letherhead can breath fire.
- He comes back in Mazes & Mutants, with the ability to breathe fire.
- He returned Mazes & Mutants as an illusion and played the dragon for Sir Malachi's maze.
- He will return near the season finale.
- There is a little possibility Casey Jones was Leatherhead's pet owner.