Some TMNT stuff really isn't for little kids.
Chameleon was a character from Archie Comics' Teenage Mutant Ninja Turtles Adventures issues #9: Codename: Chameleon and issue #51: Chameleons are Forever. He also appeared in a children's book adaptation of issue #9.
Teenage Mutant Ninja Turtles Adventures
In issue #9: Codename: Chameleon, a secret agent known only by his codename, Chameleon, is in fact a notorious double-agent who works for both the good guys and the bad guys.
The double-agent was fleeing from the police. To make his escape, the spy heads down into the sewers, and as Fate would have it, he arrives at a crossroads where he runs into the turtles along with Bebop and Rocksteady! Rocksteady nabs Chameleon, and as the turtles prepare to bonk heads, a Foot Soldier shows up on a Knucklehead. The contraption proves to be enough of a distraction to allow Bebop and Rocksteady to escape with the Chameleon.
The two bogus baddies haul the agent to the Shredder, who wants the plans that Chameleon has stolen... but the spy doesn't have them with him. Shredder demands the secret documents, so Chameleon offers to sell them to the villain... but this only angers Shredder. The nasty ninja brings out a real live chameleon and a spray can of mutagen, explaining to the double-agent that if he doesn't reveal the hiding place for the plans, he will be turned into a mutant. Chameleon complies with Shredder's demands, and Bebop and Rocksteady hurry off to retrieve the weapons blueprints. Shredder, being a dastardly villain, decides to mutate Chameleon anyway! But once he is mutated, Chameleon changes his colors and makes his escape.
Chameleon retrieves the plans from their hiding place and makes another escape! The blueprints were than mysteriously returned, with a note pinned to them saying "Some things are not worth profiting from." As the issue ends, we see the mutated Chameleon watching the report from outside a department store window, grinning.
In issue #51: Chameleons are Forever, in Tel Aviv, Israel, some criminals are planning their next heist when they discover that the nearby maid is actually a spy. They capture the woman and point guns at her, when suddenly the cart that she was pushing turns into the Chameleon, who grabs the woman and makes their escape by crashing through a window. One of the crooks wonders if they should cancel their robbery, but the ringleader states that he shot the Chameleon and that they're 20 stories high, so nothing could survive the fall—thus they'll proceed to New York City as planned.
Later, the "maid", Val, is bandaging the Chameleon's wounds. The mutant explains that he was able to morph into a parachute to save them from plunging to their deaths. Chameleon flirts with Val, but she states that she doesn't get romantically involved with her business partners, and even if she did - he wasn't her type. Chameleon morphs into a dashing, muscular blonde dude and states that he can be any type she likes - but the effort of the transformation reopens his wound and he falls to the floor in pain. Val states that she hopes he learned his lesson as Chameleon slumps into a chair, dejected. The two ponder whether or not they should follow the thieves to New York to fulfill their obligation to their employer. Chameleon turns on the TV just as "Inside Affair" comes on. The tabloid TV show is airing the footage of the turtles that was taken back in issue #47: The Eyes of Sarnath. Upon seeing the Turtles, Chameleon states that it's time for them to head to New York.
In the Big Apple, sleazy reporter McIntyre is raging at his crew to find the TMNT and to follow April O'Neil "night and day". After the TV crew leaves, we see the "Inside Affair" sign morph into the Chameleon, who calls his partner Val and tells her to dig up all the info she can on April. Val isn't happy that her partner is using her time to investigate a non-paying gig, but the mutant pleads with her to help him locate the turtles since they were there when he mutated and might be able to answer some questions for him.
Meanwhile, the robbers have made their way to the City and begin making final plans. Outside their window, a strange gargoyle sits. Once the men vacate their room, the gargoyle morphs into Chameleon, enters the hotel and reads their plans.
In the sewer, the Turtles are relaxing when Donatello spots a shadowy figure that looks like April, running away from them. Puzzled by her actions, the TMNT give chase and spot her on the roof of a museum. The lads are suspicious, but enter the building to see what's going on. Inside they find the clothes that "April" had been wearing, but she's nowhere to be seen. Suddenly, one of the mummy sarcophagi springs to life in the form of the Chameleon and captures Michaelangelo. A battle ensues and the Turtles manage to tie up their attacker. The Turtles demand to know what the story is, and Chameleon asks them if he can ever return to his normal form again—and if the Turtles can ever return to their "human" forms. He thought that since they're friends of the Shredder, they should know. The turtles angrily state that they're not friends of Shredder's and that they've never been human—although they were transformed by Mutagen, just like the Chameleon was—and as far as they know, the change is permanent. This information depresses Chameleon.
Suddenly, Leonardo hears a noise on the roof. Chameleon notes that the thieves have arrived, and then attacks the distracted turtles, knocking them cold. The shape-shifter mumbles that since the turtles were of no help, he'll have to try to salvage something from this "bummer night." The dejected mutant walks off into the darkened corridors of the museum.
The turtles awaken to find a smashed glass case and alarms going off. The guys think the Chameleon stole whatever is missing and take off before the police show up.
Outside, the thieves wheel a large wooden box and gloat over their success stealing "the statue." Little do they realize that the box they have the item stored in is none other than the Chameleon in disguise.