Mecha Robotnik (3236-3237), or M for short, is a character that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. She was the robotic "daughter" of Dr. Eggman and sister of A.D.A.M.. Loyal only to Eggman, Mecha was as cold and emotionless as most of his creations—most of the time. She only showed emotion on a handful of occasions, usually when Eggman was threatened. At these times, she became extremely angry and volatile.
Once A.D.A.M. gained self-awareness and started sabotaging Eggman's operation, Eggman became paranoid and ordered M to self-destruct, an order she obeyed.
Mecha resembled a human woman in a sci-fi version of 80's New Wave attire. She had brown hair and white skin, and wore a silver and black uniform with jewel earrings and sunglasses. When her skin coating was destroyed by a grenade, it was revealed that she had a skeletal metallic form underneath it.
During Sonic's time in space, when everyone thought Sonic was dead, Eggman created Mecha and accidentally her computer virus "brother" A.D.A.M. Mecha acted as Eggman's main bodyguard after her creation. She first came into contact with Sonic the Hedgehog and Miles "Tails" Prower when the two arrived to stop Eggman from launching his nuclear missiles from his battle ship in Old Megaopolis harbor. While Tails tried to keep A.D.A.M. occupied, Mecha gave Sonic a thrashing for attacking Eggman. Her orders were to make sure Sonic was stopped. Sonic managed to lead her away from Eggman's ship and caused her to waste much of her fuel by continuously blasting at him with her laser optics. 
After she realized she needed to correct her aiming, she managed to badly wound Sonic's arm. Before she could kill him however, Bunnie Rabbot knocked her away, while Geoffrey St. John threw a grenade where she landed. The resulting explosion ruined her outer shell and left only a metal skeleton-like construct. While Bunnie and Antoine took off to stop Eggman, from launching the nuclear missiles, Mecha recovered to attack Sonic, Espio the Chameleon, Geoffrey and Hershey St. John and Fiona Fox. The fight ended when Sonic used his speed to carve a circle of road out from under Mecha, causing her to fall into the sewers and short circuit her now-exposed systems.
Despite this, she was eventually repaired and volunteered for an assault on Angel Island after Sonic, Knuckles the Echidna and the Chaotix started devastating the work of Kage Von Stryker. Eggman had a different operative in mind, though admitted he knew Mecha would make him proud if she went.
Defending Eggman from the Metal Sonics
Mecha remained out of sight until much later, when she was seen watching over Metal Sonic's attempt to acquire information on Project: Shadow. Shadow showed up seeking the same information and fought Metal Sonic until they knocked each other out. Mecha took them away and later interrupted a meeting between Eggman, Sonic and Rotor regarding a potential assassination attempt. Unfortunately, she was somehow under control of the unseen assassin, who sent roughly 100 Metal Sonic Troopers to kill Eggman. Mecha knocked Sonic and Rotor unconscious and had Eggman cornered, while A.D.A.M. became somewhat unresponsive. Eggman managed to override the unknown villain's control over Mecha and fled, finding Shadow and the broken Metal Sonic in the process. Mecha stayed with Eggman, while Shadow helped Sonic and Knuckles stop the Metal Sonic Troopers. This fiasco would eventually cause Eggman to trace the mastermind to an upstart called "Anonymous". 
"Betrayal" and Death
The Anonymous investigation was still unfinished when Eggman explained to Mecha why he used the Egg Grape Chamber the way he did. Just as Eggman finished his mass killings, the Arachne Clan attacked intending to use the Sword of Acorns to open the Zone of Silence and release Ixis Naugus. Mecha tried to zap the Arachne Clan with her optic lasers but missed, nearly hitting Eggman. Frustrated, Eggman ordered Mecha to take him out of the chamber and had A.D.A.M. trap the Arachne Clan inside, exactly as "Anonymous" hoped. When they reentered the Egg Grape Chamber, Naugus was now present. Mecha tried to blast him, but he vaporized himself, then attempted to asphyxiate Mecha. Because Mecha didn't need to breathe and was thus unaffected, Naugus instead froze her before he warped out of New Megaopolis with the Arachne Clan and Sword of Acorns.
Just as Mecha finished defrosting, A.D.A.M. showed a video of her conspiring with "Anonymous", with "Anonymous'" identity (as usual) obscured so that Eggman could not identify him. Mecha found herself unable to explain this and claimed that A.D.A.M. was lying. Unable to prove her innocence, she had no choice but to obey Eggman's order to self-destruct. Eggman then ordered A.D.A.M. to delete all of Mecha's back-up files so that she would never return. Still, he showed deep regret with having her destroyed, when he told Sonic that he lost a lot thanks to Naugus, Mammoth Mogul and "Anonymous".
- Mecha's appearance bore many similarities with the villain T-X from Terminator 3: Rise of the Machines.
- Writer Ian Flynn stated in a Q&A on his forum that he would have liked the chance to flesh out Mecha, but was ordered to kill her off in Sonic the Hedgehog #163.
- Sonic the Hedgehog #130, "Home Part 1: The Blue Blur Returns"
- Sonic the Hedgehog #132, "Home Part 3 - A.D.A.M. & Evil"
- Sonic the Hedgehog #133, "Home Part 4: Finale"
- Sonic the Hedgehog #140, "Return to Angel Island Part 3: How Many Echidnas Does It Take to Protect a Master Emerald?"
- Sonic the Hedgehog #157, "System Shutdown"
- Sonic the Hedgehog #158, "System Reconfiguration"
- Sonic the Hedgehog #159, "System Reboot"
- Sonic the Hedgehog #163, "The Darkest Storm Part 2: Onset Of The Squall"
- Sonic the Hedgehog #164, "The Darkest Storm Part 3: Downburst"
- Ian Flynn (11 January 2009). Ask Ian for Jan'09 - New Year, Old Favorite. BumbleKing Comics. Archived from the original on 2 November 2015.