John Corben was once a jack of all trades mercenary but when he was diagnosed with a terminal illness he is given another chance by LexCorp and turned into the cyborg Metallo powered by a kryptonite heart, making him one of the most dangerous of Supermans foes
Corben was a mercenary doing dirty work for anyone who paid him. This led him to the employ of the Regent of Kaznia who hired him and his men to steal a power suit from Lex Luthor. Luthor let him steal the armor but Corben is stopped by Superman and put in prison. While in prison he is diagnosed with a terminal illness as a way to save his life he turns to Luthor who transfers his consciousness into a robots body powered by a kryptonite heart.
Corben is a former war time journalist working for the Daliy Planet in Afghanistan. He has a noted grudge against the vigilante the Blur (Superman) blaming him for the death of his sister. Because the Blur had saved a bus full of convicts of which one escaped and murdered Corben's sister.
After being hit by a bus Corben is fit with various cybernetic enhancements and is now powered by a Kryptonite heart. After seeing Lois talk to the Blur he kidnaps her in hopes of drawing him out. During the battle Blur melts a large amount of lead and covers Corben's exposed heart allowing him to fight more effectively. When Corben rips the lead off he also rips out his heart casuing him to die or power down. His body and heart are taken by Tess Mercher who's men reveal he is more man than machine and needs to simply be powered up once again. Mercher goes to the Toy Man who explains to her how the Kryptonite heart works.
Mercher reactivates Corben and plans to use a mind control chip to make him her lapdog. Lois Lane who was undercover saves him allowing him to escape. He goes back though feeling obligated to save her for saving him. After saving Lois he collapses in a basement and is discovered by Lois once again. His green Kryptonite heart is changed out for a red one and he is once again reactivated. With this new power source he helps cure Clark Kent of red Kryptonite poisoning.
Years later he joins the Legion of Doom and Supergirl is sent to capture him.
Lois and Clark: The New Adventures of Superman.
Corben after robbing a bank and being stopped by Superman has a heart attack and sent to the hospital. When he recovers he murders his doctor but while escaping he has another attack which sends him into a tree and he presumably dies. He is not though and is taken by a scientist and transformed into the Kryptonite powered Metallo. He uses these new metal parts to battle Superman but is stopped when Superman melts his legs keeping him glued in place.The scientist in his retreat steal Corben's heart leaving him turned off.
Superman: The Animated Series
Corben and his men are hired by the Regent of Kaznia to steal the powersuit Lexo-Skel Suit 5000 from Lex Luthor. The Regent and Luthor planned the whole theft letting Corben escape with the suit. Lois Lane tracks him to Metropolis and is captured by them. Superman intervenes saving Lois and stopping the mercenaries. Corben battles Superman with the powersuit but it is not strong enough and he get's captured. While in prison he has a mysterious backer who supplies his cell with many luxuries. While in prison Corben is terminally diagnosed with a disease. With the help of Lex Luthor he escapes where Luthor offers to save his life by letting his scientists transfer his consciousness into a android body.
After the process is complete Corben is extremely happy with his new powers and he battles Superman and nearly defeats him. He discovers though that he can no longer feel or taste anything in the outside world. When the scientists tells him they can not fix this he goes insane and attacks Luthor who reveals he also infected him with the disease in order to let him experiment on Corben. Superman saves Luthor from Corben's wrath who sinks to the bottom of the ocean due to his weight.
Corben later reappears on a island. Suffering from amnesia and is discovered by the local children. They at first believe him to be a hero since he looks like a action figure but when he sees a image of Superman he remembers who he is and that he is not a hero. When Superman shows up helping to evacuate the islanders Metallo attacks hurting Superman badly. Superman gains the upperhand by ripping out Metallo's heart throwing it into the lava, sending him after it into. He becomes encased in it though unable to do anything trapped inside his body.
Metallo eventually escapes his prison and joins a group of villains looking to get revenge against Superman. This group consisted of him Livewire, Toyman, Kalibak and Weather Wizard. During the battle with the Justice League he is stopped by the Martian Manhunter.
He than joins the Legion of Doom going to the underground world of Skartaris helping the dictator Deimos in for a rather large chunk of Kryptonite. The Justice League interfere and he battles the Green Lantern John Stewart,Stargirl and Supergirl. After losing an arm while fighting Stargirl Supergirl rips out Corbens heart and is captured.During the interrogation he is reminded that without the Kryptonite battery his body will shut down in mere seconds as he begins to talk his body short circuits and seems to die.
Superman/Batman: Public Enemies
Corben is reactivated by the now President Lex Luthor and put on his secret service. When Luthor goes to meet Superman Corben defends the president as Superman begins to attack. He battles Superman showing off his improved healing capabilities and the ability to morph his body into various weapons. Superman escapes after Batman blows Corben into multiple pieces.
Later that night when he is reformed he is murdered by Major Force, eventually Lex Luthor blames the murder on Superman and Batman.
Corben when he was a man he only cared about money working as a successful mercenary. When he is transferred into his new robotic body he goes insane after realizing he can no longer feel,taste or smell the outside world.
His insanity seems to be cured as he grows used to his new body and goes back to mercenary work and wanting money.
As Metallo his android body is powered by Kryptonite giving him ample power to battle the likes of Superman and Batman. The Kryptonite heart also serves as a weapon when battling Superman since it is his only real weakness.