Some TMNT stuff really isn't for little kids.
Baxter Stockman is a human who has been a career businessman, scientist, inventor and politician. He was the owner of StockGen, and later founded the Techno Cosmic Research Institute, and is currently the Mayor of New York City. A cunning survivor and sociopath whose only friend is himself, Baxter has been secretly involved in shady ventures for years, and since working with General Krang has also has been deeply involved in genetic and mutant research. Under Baxter's management, he invented the Minefield Ordnance Unarming System Enhanced Robotss; Splinter was given his sentience and reunited with his reincarnated sons, the Turtles; Krang gained the technology to create his Stone Soldiers and finish building his Technodrome; the mutations of Slash, Wingnut, Screwloose and the flyborgs occurred; and his StockGen employees John O'Neil, April O'Neil, Zayton Honeycutt and Lindsey Baker were introduced to the world of mutants.
As a young boy, Baxter's father Robert Stockman taught him how to play chess as a method of honing his skills, intelligence, and tactical abilities. Baxter, in turn, later used these attributes to take StockGen away from his father. Under Baxter's management, John O'Neil, Lindsey Baker and Chet Allen became employed at StockGen, and John's daughter April O'Neil came to work there as an intern.
Baxter would later do business with the mysterious warlord General Krang, who provided him with the resources to create a supersoldier mutagen, a psychotropic compound to enhance intelligence, and biological body armor based on turtle shells. However, these projects attracted the attention of the Shredder, due to the covert intervention of Chet Allen. Much to Stockman's dismay, both the mutagen and the psychotropic compound were stolen and lost.
Over the next several months, Baxter would use the mutated alley cat Old Hob to hunt the former lab rat Splinter in hopes of reclaiming an untainted sample of the psychotropic compound. His relationship with Krang also became strained, as Baxter had failed to complete two of the three scientific projects he had been contracted for.
He eventually allowed Old Hob to use his robots, named Minefield Ordnance Unarming System Enhanced Robots (or MOUSERs, for short), to capture Splinter. While Splinter was soon lost to StockGen for the second time, Baxter's technical skills impressed Krang. Baxter was drugged and transported to Burnow Island, where he found that Krang was an extra-dimensional Utrom who wished to use his engineering abilities to complete a terraforming fortress known as the Technodrome.
During his time working on the Technodrome, Baxter attempted to undermine Krang by installing malware in the computer systems, and even attempting to kill the Utroms in cryostasis. He formed an uneasy alliance with Zayton Honeycutt, but the robot scientist turned against him when he learned that Baxter planned to take control of the Technodrome as a weapon. Baxter interfered with Honeycutt and the Turtles' attempts to stop him by unleashing an army of MOUSERs, but Krang easily dispensed with his malware. Defeated, Baxter used flyborgs to flee the Technodrome.
Upon his escape from the island, Baxter used flyborgs to rescue the suffocating Shredder, and proposed a mutually beneficial partnership, showing Shredder his new headquarters at at the Techno Cosmic Research Institute (or TCRI, for short). At the Shredder's behest, he began using flyborgs and MOUSERs to hunt down Splinter, but his creations were destroyed by a squad of Foot Ninja led by Oroku Karai. When Splinter challenged Shredder to the Gauntlet, a disgusted Baxter left the Foot Headquarters.
Sometime later, he was confronted by April O'Neil, and was shocked to discover that she knew all about his prior dealings with Krang and the Shredder. However, before he could respond to this revelation, the building was invaded separately by the mutant scorpion Zodi working for Madame Null and a small army of Darkwater mercenaries working for Jonathan Bishop, forcing Baxter to ally himself with the Turtles in order to survive. After the conflict concluded, he reluctantly accepted April as his new partner.
Baxter found himself working with them again when the Turtles needed to be teleported into the Pantheon's family reunion at the Den of Delights, which he only did with the promise of financial gain. During the war between the Earth Protection Force and the Triceratons, Baxter benefited from the crisis by selling essential supplies to citizens who were trapped in their homes. He played an important role in the invasion's conclusion, using a teleporter to transport all the Triceratons on Earth to Burnow Island. Due to the intervention of Elizabeth O'Neil, he was able to take full credit for stopping the invasion single-handedly. However, immediately after a press conference, he was taken by Detective Kara Lewis to see Agent Bishop, who obtained the current location of the Triceratons from him.
April continued advising Baxter in how to further enhance his image in the city, suggesting that he could use his MOUSERs to deal with the burgeoning rat problem, while knowing that the Rat King was causing it. Baxter agreed, and the unleashing of his robots helped the Turtles to triumph over the Rat King, as well as unearthing the presence of Leatherhead. Baxter then publicly declared his candidacy for the office of Mayor of New York City, a goal which he later achieved with April's help.
The Union Square Park celebration for Baxter Stockman's election was infiltrated by Old Hob and Man Ray of the Mutanimals. Hob rushed the podium, forcing Baxter and April to flee, and Hob both shared his manifesto with the world and detonated a mutagen bomb, quickly mutating hundreds if not thousands of New Yorkers. As mayor, Baxter declared a quarantine zone in the parts of Manhattan's East Side most contaminated by the bomb's mutagen fallout, built a fifty-foot wall around it, and with the Earth Protection Force's involvement, evacuated the zone's unmutated human population and forced the mutated humans to live inside the zone until their mutations could be reversed and the area decontaminated, neither of which was to happen anytime in the foreseeable future. Within this quarantine zone, the mutant inhabitants and the Mutanimals formed the new community of Mutant Town.