Dr. Baxter Stockman is a scientist who has appeared in several versions of the Teenage Mutant Ninja Turtles show and comic. In each version, he is depicted as the creator of the Mousers, machines meant to seek out rats (not mice). However, there are several differences between his various appearances.

Old TMNT Cartoon Series: 1987

In this lighthearted show, Stockman was a bumbling Caucasian inventor who tried to bill his Mousers to the Ajax Pest Control company. They did not like his suggestion, saying it would put them out of business, and threw him out of the building. The Shredder had watched this via his cameras, and offered Stockman a job. Baxter promptly accepted, and Shredder ordered him to create a "master control device" for the Mousers. Shredder, not being able to wait, used a replication device on the Technodrome to assemble twelve Mousers. He then programmed the Mousers to find and destroy Splinter, the rat-man who was the Turtles' master. The Mousers are destroyed by the TMNT, and they find Stockman's name on the devices. The Turtles and Splinter find Dr. Baxter Stockman with April O'Neil's help, and he tells them his part of the story. They then proceeded to take Stockman's van, later to become the Turtlevan. After a failed Mouser attack, Baxter helped Shredder to get the Three Fragments of the Eye of Zarnov. Once this attempt failed, he was placed into a disintegrator by Krang. A common housefly accidentally flew into the disintegrator, creating Baxter the Fly. The Fly left Shredder and Krang later, after several failed attacks together. He appeared as a guest villain in a few later episodes, and then was abandoned in Dimension X prior to the appearance of Lord Dregg. He was voiced by Pat Fraley in this show.

Laird & Eastman Comics, Volumes 1 and 2

In the comics, Dr. Stockman was an African-American mad scientist with no relation to the comic Oroku Saki, or Shredder. He developed the Mousers, with the help of his computer programmer April O'Neil. Around the time of the Mouser's invention, strange bank robberies were being held, with small tunnels leading into the vaults. When April questioned Stockman, he led April to an underground factory where hundreds of Mousers were being made. Stockman revealed he had been using the Mousers to rob banks, not because of the money (he could use his invention to make millions legally), but because "it was FUN!" April tried to escape through the elevator, but the scientist sent the elevator to sewer level. The Turtles saved her from the Mousers Stockman had sent to kill April. They successfully infiltrated Stockman's lab, and managed to stop him. He was taken into custody. Later, he reappeared in Volume 2 as a major villain who had used technology from DARPA to place his brain in a robot body, making him a cyborg. Stockman tried to get revenge, but his new body was electrocuted and destroyed, and only the glasses he had retrieved earlier remained. In Volume 4, it is suspected he injected April with nanobots to make her sterile.

New TMNT Cartoon Series: 2003

Baxter Stockman was African-American in this show, like the comics. The first Stockman plot was similar to that of the comics, but he was working with the new series' Shredder and was robbing banks for him. Instead of being taken into custody, Shredder punished him, presumably removing or disabling his left eye. In this form, he captured Raphael, with the help of Foot Tech Ninja he had made based on an old exoskeleton found by the Foot. Dr. Stockman questioned him on his species, threatening to kill him and let his DNA reveal it. Raphael escaped, and Stockman was once again punished, this time with his arm being replaced by a robotic counterpart, and his legs disabled so he needed a wheelchair. At this point, the TMNT were hiding in Casey's grandmother's house, having barely escaped their last encounter with the Shredder. Shredder wanted proof of their death, so Stockman offered his DNA analysis system in exchange for full access to the exosuit. Having found no proof, he lied to Shredder on their deaths and was given the exosuit. During the Return to New York three-parter, Dr. Stockman reappeared, in a giant robotic suit presumably based on the exoskeleton. The Turtles and Shredder had a hard time fighting him. Finally, Donatello defeated Stockman, blasting his suit to pieces. Stockman reappeared during the battle with the Utroms , now only a head in a spider body. Shredder controlled Stockman using a robotic eye placed where he previously had an injury, now with the ability to shock Stockman into following him. With the help of the Fugitoid, he was freed from the control of Shredder, and turned against him, knocking him out. Shredder returned minutes later, and Stockman escaped. He briefly reappeared with the mutant Leatherhead in an Utrom exosuit, saying he was Leatherhead's "friend." Stockman once again escaped, managing to get rid of Leatherhead in the process. During "City at War," he reappeared, now with the Mob. He was on top of an exosuit during that time, but failed, finally being shot down. He makes a few appearances during "Rogue in the House," now just a brain and eyeball with the Foot, connected to a machine that allows him to speak. After the Foot base was destroyed, Stockman sunk underwater. It is not known what has become of him since. Scott Williams was the voice actor for Stockman in this show.