Hyper Metal Sonic is a robotic duplicate of Sonic the Hedgehog. A frequent enemy in the Sonic video games, it is also the co-antagonist of the Japanese Sonic OVA.
Hyper Metal Sonic (often simply referred to as Metal) was created by diabolical scientist Dr. Eggman (known as Dr. Robotnik in the English dub). Modelled on Sonic the Hedgehog's appearance and possessing superior abilities, Metal was designed for the specific purpose of killing Sonic and helping Dr. Eggman conquer the planet Freedom. When Eggman completed Metal's body, he then concocted a scheme to lure Sonic into a trap and capture the hedgehog's life data, completing the robot's programming by adding all of Sonic's personality and thought patterns.
Dr. Eggman gained Sonic's data by staging a disaster in his home city of Eggmanland (Robotropolis in the English dub). A robotic alternate-universe version of Eggman called "Dark Eggman" (Metal Robotnik) had supposedly invaded the city and sabotaged its power generator which would explode and destroy the entire planet if it wasn't shut down. Eggman pleaded to Sonic and Tails to shut down the Egg Generator and defeat Dark Eggman, and Sonic reluctantly agreed. Sonic and Tails travelled to the Land of Darkness - Planet Freedom's inner dimension - and headed for Eggmanland, but were stopped in their tracks by Dark Eggman (which unbeknownst to the heroes was just a giant mecha that Eggman was pilotting). After a lengthy battle that was only won thanks to the intervention of Knuckles the Echidna, Sonic defeated Dark Eggman and he and his friends ventured onward to Eggmanland.
Metal Sonic Awakens
Sonic succeeded in shutting down the Egg Generator, but was caught in a trap and appeared to be electrocuted. This was not the case; the machine had copied Sonic's life data and transferred it to the dormant body of Hyper Metal Sonic waiting in the lowest levels of Eggmanland. With its programming completed, Metal Sonic awoke. Dr. Eggman appeared moments later and revealed the details of his scheme to acquire Sonic's data, then ordered Metal to destroy his counterpart. Sonic and Metal fought but the robot had the clear advantage, possessing superior strength, speed and the ability to fly. Eggman monitored the fight from his Eggmobile aircraft and was overjoyed when Sonic's vital signs dropped. With Sonic supposedly dead, Metal Sonic and Dr. Eggman moved on to the Land of the Sky, the outer dimension of Freedom.
Without interference from Sonic or his friends, Hyper Metal Sonic went on a rampage across the Land of the Sky. Its first stop was Sonic's house on South Island, where it found Old Man Owl watching the house and dressed him up in Sonic's favourite clothes (even though Sonic never really wears clothes). Metal then proceeded to attack numerous cities across the world, causing a great deal of damage and confusing the citizens who believed they were being attacked by Sonic. The President of South Island contacted Sonic's house and got in touch with Knuckles and Tails, who told him the whole story and explained that Metal was likely going to attack the Northern Glacier that held the planet's continents together. If the glacier was destroyed, the continents of the Land of the Sky would be thrown into orbit by the planet's rotation and annihilated.
Sonic, who had barely managed to survive his first battle with Metal Sonic, arrived at the Presidential Command Center and overheard the entire conversation between Knuckles and the President. He then proceeded to run across the planet to the Northern Glacier where he battled Metal once more. Dr. Eggman also arrived on the scene with the President's captive daughter Sera and Tails and Knuckles later arrived to give Sonic a hand. The President himself even came to the glacier, but his rocket crashed and was at risk of exploding due to the magma running beneath the glacier. Sonic tried to get to the President and Tails was able to help by hacking into Metal's programming, bringing out Sonic's personality. The battle continued until Sonic sent Metal crashing into the President's ship. The ship exploded, but the President survived when Metal Sonic saved him, apparently now guided by Sonic's personality engrams.
As Metal Sonic released the President, it was struck by a piece of falling debris and fell into a magma-filled crater. After witnessing Metal's act of heroism, Sonic jumped down to the crater to try and save his robot double. The badly damaged Metal crawled up the side of the crater as Sonic held out his hand to grab him, but Knuckles held Sonic back believing that Metal would just drag Sonic down into the magma with it. Instead, Metal reached out for Sonic's hand then slapped it away. It stated "There is only one Sonic" and then let itself sink into the magma where it met its end.