Instead of a villain as was his previous animated incarnation, Leatherhead was an ally to the turtles with a scientific mind like Donatello. He is voiced by F.B. Owens in seasons 2 and 3 and by Gary Lewis in seasons 4 and 7.
Leatherhead was originally an exotic pet who got flushed down to the sewer, somehow ending up in an Utrom base. After being exposed to the same mutagen that would eventually change the Turtles, Leatherhead became a massive, humanoid crocodile. He lived with the Utroms whom he considered his family. He was accidentally left behind during the Shredder's attack, which forced the Utroms to flee Earth.
Leatherhead first made a shadowed cameo in Secret Origins, Part 3 escaping from the TCRI building during the raid. He was first seen in the episode What a Croc, where he was helping Baxter Stockman create a new body, while working on a transmat device so he could rejoin the Utroms and had built the Turtlebot. Leatherhead eventually met and befriended Michelangelo who found him living in the Turtles' old lair. Unfortunately for Stockman, the doctor accidentally allowed Leatherhead to know he once worked for Shredder; since the Utroms had adopted and told him about the Shredder, Leatherhead immediately got angry. Eventually Stockman bombed the location and despite Michelangelo's pleas for him to follow them Leatherhead sacrificed himself to save the Turtles.
Later in season 3 it was revealed that Leatherhead had in fact survived the ordeal, but had been taken captive by Agent Bishop. The Turtles soon helped Leatherhead escape and for a time lived in the Turtles' lair. However, Leatherhead's animal rages, already dangerous, were made more so by Bishop's experimentation. While in blind animal rage, Leatherhead struck Michelangelo, and woke up to believe that he had killed his friend. Leaving the Turtles, a depressed Leatherhead found himself hunted by an extreme game hunter, Mr. Marlin, through the sewers. Luckily, he was saved by his friends who refused to give up on him, and was delighted to discover Michelangelo was alive and well. In the end, he chose to live away from his friends due to his affliction, living in a nearby chamber (an abandoned subway) so he would always be nearby, but still able to ensure their safety. He reappeared in a number of subsequent episodes as an ally to the Turtles primarily in their battles with the Foot and Agent Bishop, including the raid on the Shredder's building facing Hun, during the battle the two fell into the silo. Both survived, and Leatherhead returned to his lair but lived by himself to avoid accidentally hurting the Turtles due to his anger issues that furthered increased from Bishop's experiments on him. He is later revealed to have helped Donatello create the Monster Hunter gear used by the Turtles against Bishop's mutant creatures.[[
During the fourth season, Leatherhead played an important role in working together with Don in containing the mutation of local creatures from the mutagens that were created by Baxter Stockman previously during his faked alien invasion. However, when Donatello is accidentally exposed to the mutagen, Leatherhead works with the other turtles in capturing the mutated Don. Leatherhead later discovered that the combination of the mutation from Bishop's outbreak was mixing with the original Utrom mutagen in an unstable way, it would kill Don unless if it was cured.
Leatherhead worked with the Turtles and Splinter in breaking into Area 51 where Bishop was. While Bishop sent the three turtles to steal the Heart of Tengu from Karai, he was forced to fight the mutated Donatello. Reminded of the trauma he had suffered, he was tempted to extract revenge on Bishop but managed to control his anger with the help of his friends. Despite his personal grudge against Bishop, Leatherhead was able to use the details that Bishop and Stockman had on the new mutagen, and using Bishop's resources, he is able to cure Don, and the other animals mutated from the outbreak.
Back to the SewerEdit
Leatherhead can be seen in Donatello's memory in the episode Identity Crisis. Leatherhead appears in attendance for Casey and April's wedding in Wedding Bells and Bytes. He is spotted crying, and gives the wedding as the reason. Leatherhead helps save the other guests as the barn collapses and then helps fight the Foot.