Leatherhead

Leatherhead is a mutant alligator that lives in the same city as the Turtles. Leatherhead first mutated on Burnow Island during the 18th century, and is at least that old. His mutation came when a nearby pirate ship unloaded some of its cargo into the water, which included canisters of mutagen. Leatherhead was named by the island's former indigenous inhabitants who only saw him in brief glimpses, and nicknamed him "Leatherhead of the Lagoon."

During his life before the Turtles were born, he was captured by Krang, enslaved, and studied. Since he was treated so harshly, he has developed a hatred of Utroms in general and Krang in specific. He appeared as a witness in the Trial of Krang.