Justin

Justin is a new mutant that shortly appeared in The Alien Agenda. It is mixed with several DNA specimens.

Physical appearance
Justin is combined with several specimens. He has a pink octopus body with approximately 8 tentacles, a snake-like neck with a lined mouth filled with sharp teeth and fangs and a large, blue isopod shell on his head. He has a red, forked tongue, purple jellyfish holding his yellow eyes, which are lined with stalks, and yellow, green and orange piscine fins, which slightly resemble a cobra hood. His orange ears are pointed like those of a cat.

Powers and abilities
Justin is able to expand and contract his neck to show his mouth, display his cobra-looking hood, stretch his stalked eyes and shoot electricity from them, and meow like a kitten (possibly to lure prey to attack them).

Season 1
Justin was created when the DNA samples in the Worldwide Genome Project were mixed together in mutagen because Karai pressed a button. Later, a hybridized mutant emerges from the ooze, and grabs several Kraang with its tentacles. He looked at the Turtles and meowed, making Mikey think he's so cute. Justin then expanded his neck, stretched his stalked eyes and displayed his fin-looking cobra hood. Mikey is confused by its appearance and may not figure out how to name it. Justin then attacks the Kraang and the Turtles before Karai leaves them, while she takes a damaged Kraang-droid, much to Leo's horror of her betrayal. As the Kraang are finished off, he grabs Raph, but he gets out of his grip and calls him "Octo-punk". Justin swats him as Mikey tells him to call the mutant "Octo-Eyeball-Jelly-Bug". However, he finds it to not fit right and decides to call it Justin. Mikey then gets slammed on the wall, Raph on the floor, and Donnie gets zapped by its electricity. Leo then fights off Justin by hitting him a few times, but bounces off his shell. He slides down on one of his tentacles and slams him on the ground. Leo then tells Justin that it ends now. Justin uses his electricity as Leo uses his katanas as a conductor. He slams his katanas on the machine, causing an explosion to set Justin on fire. The mutant shrieks with pain as he flees, believed to have died.

Season 2
In Metalhead Rewired, Justin makes a surprise appearance. He somehow survived the fire, and now he's one of the many detained mutants captured by the Kraang so they can control them. When the mutants were released by Metalhead, Justin is seen with Spy-Roach as he crawls out of his cell. A Kraang-droid (which Rockwell attacked) shot the mutant as he falls several feet to the ground. Luckily, he managed to survive and then headed to the portal.

Trivia

 * Justin is combined with several DNA samples from a jellyfish, an isopod, an octopus, a cobra and a cat.
 * There were other DNA samples like rooster, crocodile, narwhal, giraffe, wasp, praying mantis, mountain lion, hippopotamus, snake, kangaroo, crab, bat, beaver, lizard, caterpillar, and bull. There were some unsual specimens like a cotton candy-looking icon, an icon that resembles a robot's head, an unknown specimen with a question mark, a donkey-looking specimen, an Ankylosaurus-like specimen, a weasel-like specimen, and a curved looking specimen.
 * Justin also appeared in the 2013 video game.
 * It's possible that Spy-Roach would be his partner in the future.
 * It's possible Justin extinguished himself before the Worldwide Genome Project was destroyed.
 * His appearance made it confusing to make Mikey give it a proper name that would fit it.
 * Mikey thought Justin was so cute just because he meowed like a cat.