Baxter Stockman

Baxter Stockman, is a brilliant scientist.

Mirage Comics
Baxter Stockman is a brilliant scientist that used his talents for his own selfish nefarious schemes rather than to help mankind. His latest invention, the Mousers, were small robots designed to find and kill rats, thus solving the city's rat problem. However, Baxter was really using the Mousers to rob banks and commit other crimes. Once his assistant April O'Neil discovered his plan, he sent the Mousers after her. Not knowing that she was saved by the TMNT, he continued his plans, holding the city ransom with the threat of destroying several city landmarks with his Mousers. With the help of April, the TMNT found Baxter, defeated him, and sent him to jail.

In Volume 2 of the series, Baxter would somehow escape prison and break into the DARPA facility to wreak havok. After taking out the guards, he would somehow implant his brain into the body of a huge killer robot. As the robot, Baxter would bust out of DARPA, seek out and find April O'Neil and inject her with something which was, at the time, unrevealed. The TMNT, Casey and Nobody find and battle it out with the Baxterbot, which would result in Baxter escaping missing an arm and blacking out, and Raphael being captured by DARPA. Gaining consciousness, Baxter would discover his robot body was fixed and somehow regenerated an arm. The other three Turtles and Casey find the Baxterbot in the sewers, ready to electrocute them with live power lines. Leo would turn the tables and electrocute the Baxterbot instead. While the Turtles wondered how Baxter got the robot to work, they didn't know his brain was actually inside it. Or so it would seem.

In Volume 4 of the series, April would fall prey to nanobots inside her system, threatening her life. It was revealed that this was what Baxter injected her with all those years ago. It was also revealed that Donatello had part of the robot with Baxter's brain still alive and pinned up against a sewer wall. When Donatello would ask Baxter for a way to help April, the mad scientist would only laugh and say how she was doomed. In a rage, Donatello blew him up.

It is also worth mentioning that in the Mirage comics, unlike other media, Baxter Stockman was a stand-alone villian and had nothing to do with the Shredder or the Foot.

1987 Cartoon Series
In this version, Baxter would be a bumbling caucasian scientist rather than the African Americam from the Mirage comics. A humble inventor, Baxter actually started out an honest life trying to sell his Mousers to a pest control agency. Seeing that it would work a little too well to rid the city of rats, and thus, put the pest control agency out of business, Baxter was thrown into the street. Shredder would find Baxter and offer him a job, creating a Master Control System for an army of Mousers. While Baxter didn't know Shredder was using the Mousers to kill the Turtles and Splinter, Shredder still sent the Foot to eliminate him. The Turtles defeated the Foot and tied Baxter to a lamppost to interrogate him. He would be arrested and Donatello would use the equipment he found in his apartment to create the Turtle Van and the Turtle Blimp.

Baxter would later be seen in an insane asylum, by now going criminaly insane. Shredder would return to bust him out and use him to help in his attempts to defeat the Turtles. During the Eye of Sarnath arc, Baxter had enough of Shredder's abuse and tried to use the magical jewels for himself. The Eye could create things out of thin air, or transmute objects, but it had no effect on gold. Shredder would take advantage of this to get the Eye back, even though he'd still end up getting defeated by the Turtles. Despite his treacherous nature, Baxter would still remain under Shredder's employ, until Shredder demanded Krang send Bebop and Rocksteady back to Earth (since they were trapped in Dimension X at the time). Since at the time the Technodrome's dimensional portal was weakened, Krang could only send them back if he got something sent in return, so Shredder threw Baxter through the portal. Seeing no use for a human scientist, Krang had him thrown into a disentrator unit. A fly happened to follow Baxter inside, and instead of disentrating him, it would crossmutate him with the fly, turning him into a mutant fly.

As the fly, Baxter would now plot revenge against both the Turtles and the Shredder. While Shredder would sometimes trick Baxter into helping him, with the promise of turning him human again, Baxter would always be doublecrossed and twice as eager to attack Shredder the next time. Baxter's schemes would always get him trapped into either Dimension X or some other parrelel dimension. During his attempts to destroy his enemies, he would befriend a sentient computer named Z, who would try to help out Baxter, since over time, he would start losing his scientific mind and begin acting more like a fly. His last encounter with the Turtles and Shredder saw him trying to use Insect Essences to turn all of humanity into all kinds of insects. The Turtles used the Retromutagen Ray that Shredder just happened to rebuild to thwart Baxter's plans and send him back to his dimension. Ironically with the Retromutagen Gun, Baxter would have been able to regian his human form, but it never crossed his mind at the time.

Another thing worth mentioning was that Baxter was also the inventor of the device called the Knucklehead, though Shredder used it after he got rid of him. Also it was revealed that he has a twin brother named Barney Stockman that hates his brother and the fact that turned into a fly.

Archie Comics
Following the stories from the 1989 cartoon, Baxter would again try to sell off his Mousers to a pest control agency, and be thrown into the street. Shredder would use his Mousers to try to get rid of the Turtles and Splinter. The Turtles would tie up Baxter and interrogate him and leave him there to be taken away by police. Later, he'd be in an insane asylum where Shredder would again use him for his evil plans. However the Archie comics would make a radical retcon and u-turn of events during their take on the Eye of Sarnath arc. Here Shredder and Baxter managed to only find the first half of the crystal. While Shredder and Baxter were running from the Turtles, Armaggon, a mutant shark from the future, appeared and grabbed Shredder, offering safety in exchange for help against the Turtles. We assume this only left poor Baxter alone to face the Turtles and the police. It's worth mentioning that in the first 3-issue arc based on the first 5 TMNT episodes, Baxter's hair was colored white for some reason, though he was again blonde in the regular series.

2003 cartoon Series
Similar to the Mirage comics, Baxter would still be an African American scientist, working on his Mousers with hidden motives. While he sold them off as a means to rid the city of the rat problem, he was really using them to rob banks while under Shredder's employ. When his assistant April O'Neil discovered his plans, he sent the Mousers after her. With the help of the TMNT, she escaped and returned to Stocktronics to defeat him. As the building went down, Baxter was taken by Hun to see Shredder. The price for his failure was his right eye. Baxter would then use the information he got from studying an Utrom exosuit the Foot found to create the invisible Foot Tech Ninjas, in an attempt to defeat the Turtles. When that plan failed, Baxter was injured to the point that he was in a wheelchair and missing his right hand. When the Shredder had his vengeance against the Turtles (Shredder Strikes Back arc), he would send baxter to get proof that the Turtles died. Baxter made his own proof and gave it to Shredder in exchange for the Utrom exosuit to study. When the TMNT returned to New York and took revenge on the Shredder, Baxter would bust in, using a giant robot to try to get revenge on all 5. The Turtles and Shredder had to temproraily work together to defeat Baxter.

Later, Baxter would be reduced to a head on a spider robot body that was voice activated by the Shredder. Using him to sneak inside the TCRI building, Shredder would have Baxter tamper with the virtual reality program the Utroms were using to explain their origins to the Turtles, so that if they died in VR, they'd die for real. Once the TMNT broke free, Donatello had Fugitoid imitate Shredder's voice to release Baxter from his control. Now free, Baxter attacked Shredder and everyone would discover that he was actually an Utrom.

With Shredder's defeat, Baxter would set his head on an Utrom Exosuit and first try to trick Leatherhead for his own evil schemes, and later work with mob bosses in an attempt to rid the city of the Foot and the Purple Dragons, and win the gang war. Hun would somehow find Baxter again and reduce him to just a brain in a jar, and once again put him under Shredder's command. Through several of Baxter's failed attempts, a new scientist named Dr. Chaplin was introduced, who would build Baxter a new robot body that would project a hologram image of his head. While Chaplin admired Baxter's work and looked up to him, Baxter was always trying to get rid of him. Eventually Baxter would doublecross Shredder one last time and now work alongside Agent Bishop in exchange for a new body.

Baxter would finally make a new human body for himself, but his work was rushed and he also added an experimental super serum to make him stronger. While Baxter finally had a human body again, it would soon decay and he would end up losing his mind. In his insanity, he decided that all of this began when April sent the Turtles after him, so he sought out to kill her. In the end, Baxter's delusions of his mother made him save April instead, and he'd apparantly fall to his death into the ocean. Not being done with Baxter's work however, Bishop found and revived his brain, despite Baxter wanting to finally rest in peace.

In TMNT fast Forward, Baxter would still be alive after 100 years, mixing his brain with alien DNA. He sent creatures called Organic Mousers after Bishop, because he felt he was betrayed years ago when a failed experiment caused their building to collapse. Bishop was actually trying to save Baxter, and during their battle, the now reformed Bishop would save him again. Bishop would now hire baxter to work for him, and seeing that in the future making a clone body is really nothing, Baxter would finally have his normal body again and probably reform.

It is also worth mentioning that in an alternate future, where Shredder rules Earth, Baxter's brain was attached to an aged wheelchaired Hun. They were now working with the Turtles and April in an attempt to overthrow the Shredder. When they went to face him for the final showdown, Hun begged Shredder to take him back. Shredder, now using a giant-sized exosuit, stomped both Baxter and Hun flat.

Appearances in Video Games
Baxter would appear in several videogames as a boss character.

TMNT Arcade Game- Arcade/NES/Amiga/Amstrad CPC/Atari ST/Commodore 64/PC/ZX Spectrum/MSX
Baxter would appear in his human form, flying around a machine that would throw out Mousers. Since the arcade was based on the 1989 cartoon series, Baxter was caucasian. In the NES version of the game, TMNT 2 the Arcade Game, Baxter would return in a later level as his mutated fly form. He was used to replace the Bebop and Rocksteady team-up boss battle from the arcade. Baxterfly would also appear in the cutscene they were in.

Teenage Mutant Ninja Turtles: The Manhattan Missions- PC
Baxter appears in his human form in his lab while you fight Leatherhead.

TMNT IV Turtles in Time- Arcade/SNES
Baxter would appear in both the arcade and SNES versions as a mutated fly using some kind of gun that would throw our fists made out of energy. After enough hits, the gun would break, but still shoot out laser beams. It's also worth mentioning that in the Arcade Game, one of the bosses, "Cement Man", was the same Glue Monster that Baxter created in the 1987 cartoon using the Eye of Sarnath.

TMNT Hyperstone Heist- Sega Genesis
Baxter would return in human form, using the same machine he had in the first TMNT Arcade Game.

TMNT Tournament Fighters- SNES
Baxter the fly would be seen rooting for you in Donatello's junkyard level, alongside Casey Jones.

TMNT Fall of the Foot Clan/Back from the Sewers- Game Boy
Baxter would also appear in his mutant fly form.

TMNT 2003 games- PS2/Game Cube/X-Box/PC
In addition to cutscenes, Baxter was a boss in Donatello's path of the 2003 game, appearing in his giant mecha suit.

TMNT 2003 game- GBA
He appears in cutscenes

Teenage Mutant Ninja Turtles 2: Battle Nexus- GBA
He appeared as the penultimate boss bout.

Trivia

 * Ironically enough Baxter's original toy came with a Fly Swatter Meelee weapon.