This character exists primarily or exclusively within the Pre-Super Genesis Wave continuity.
Information in this article may not be canonical to the storyline of the games or any other Sonic continuity.
For the version of this transformation after the
Super Genesis Wave, see Metal Overlord (Archie).
Metal Overlord is a transformation mentioned in the comic series and its spin-offs published by Sonic the Hedgehog Archie Comics. It was a form Metal Sonic once attained in the reality created by the second Genesis Wave.
After copying data from
Sonic, Tails, Knuckles, Team Rose, Team Dark, the Chaotix, and Chaos through Froggy and Chocola, Metal Sonic eventually evolved into Metal Overlord in his bid to finally defeat Sonic and take over the world. Despite his power, he was defeated by Super Sonic and his Chaos Emerald-empowered teammates Knuckles and Tails. Sonic remembered this form as simply "that stupid dragon thing" when he later battled Metal Sonic aboard the  Wily Egg in the Skull Egg Zone.
Note: From this point, Metal Overlord's history continues from
his new life in the altered timeline.
It has been stated by head writer Ian Flynn that Archie Comics are not allowed to use Metal Overlord in the comic book series at the time being. Sonic the Hedgehog Flynn also considers Metal Overlord to be one of his least favorite Sonic characters. 
Alf Layla wa-Layla | Baker | Burning Blaze | Chaos' forms ( Chaos 1, Chaos 2, Chaos 4, Chaos 6, Perfect Chaos) | Color Power | Dark Queen | Dark Shadow | Darkspine Sonic | Devil Doom | Excalibur | Excalibur Sonic | Finalhazard | Gaia Colossus | Hero Shadow | Hyper Mode | Hyper Knuckles | Hyper Sonic | Master Core: ABIS | Mephiles' monstrous form | Metal Sonic Kai's transformation | Nega-Mother Wisp | Neo Metal Sonic ( Metal Madness, Metal Overlord) | Perfect Dark Gaia | Roboticization | Sonic the Werehog | Super transformation ( Flicky's Super State, Mecha Sonic's Super State, Pir'Oth Ix's Super State, Super Knuckles, Super Shadow, Super Silver, Super Sonic, Super Tails, Ultimate Gemerl) | Ultimate Emerl | Void's transformation
Sonic the Comic Perfect Chaos | Super Sonic
Adventures of Sonic the Hedgehog Roboticization | Super Robotnik | Supreme High Robotnik
Archie Comics Pre-SGW
Chaos Knuckles ( Dark Mobius, Light Mobius) | Chaos Shadow | Crystalline Magic ( Crystal Golem) | Enerjak ( Dark Enerjak) | Finalhazard | Metal Overlord | Perfect Chaos | Roboticization ( Blaze Woman, Charmy Man, Espio Man, Knuckles Man, Mecha Sally, Mecha Sonic, Rose Woman, Rouge Woman, Shadow Man, Silver Man, Tails Man, Vector Man) | Super transformation ( Hyper Knuckles, Hyper Tails, Master Mogul, Super A.D.A.M., Super Armor Mega Man, Super Scourge, Super Shadow, Super Silver, Super Sonic ( Dark Mobius, In Another Time, In Another Place), Turbo Tails, Ugly Naugus, Ultra Sonic ( Eco Sonic, Polar Sonic, Solar Sonic)) | Titan Metal Sonic | Titan Tails | Werehog
Burning Blaze | Chaos Shadow | Crystalmancy ( Crystal Omega, Crystal Sonic) | Devil Doom | Monster Form | Neo Metal Sonic ( Metal Overlord) | Overclocked Nicole | Perfect Chaos | Perfect Dark Gaia | Roboticization ( Blaze Woman, Charmy Man, Espio Man, Knuckles Man, M'egga Man, Rose Woman, Rouge Woman, Shadow Man, Silver Man, Sonic Man, Tails Man, Vector Man) | Sonic the Werehog | Super transformation ( Super Armor Mega Man, Super Shadow, Super Silver, Super Sonic)
Sonic X Chaos' forms ( Chaos 2, Chaos 4, Chaos 6, Perfect Chaos) | Cosmo's transformation | Dark Sonic | Final Lizard | Final Mova | Serpenter | Super Shadow | Super Sonic
Chaos Dingo | Regeneration | Roboticization ( SatAM, Sonic Underground)