Biography in Smallville
John Corben (aka Metallo) is a journalist who worked for the Daily Planet. He came to replace a missing-in-action Clark Kent, and held a personal grudge against the Red-Blue Blur, who he blames for his sister's death.
Corben has dark hair and is about average height and build. He is always seen unshaven. After his accident, he has a large metal appliance added to the front of his chest, with spider leg like appendages holding it in place and a beating green kryptonite heart in the center. He also has a robotic appliance in his left elbow.
John Corben was a reporter who lived with his sister Becca before she moved to Metropolis. He was sent to cover a mission in Afghanistan and from there he kept in touch with his sister through video messages and reminded her to be careful because she was alone in the city. During this time, a truck carrying prisoners had a mishap and was rescued by the Blur but amid the commotion, a murderer managed to escape and ended up killing Becca.
John was shattered by this news and returned from his trip to buy the building in which his sister lived. He blamed the Blur for what happened and since then he has been determined to expose him to the world. John Corben was brought into the Daily Planet as a replacement for Clark Kent who was on indefinite family leave and went to the site of the recent monorail crash to investigate a story. He snuck inside to find Lois Lane looking for clues on the ninja who attacked her. Lois at first presumed he was a detective and tried to leave but Corben played along and questioned her. When a real cop saw the two, Corben kissed Lois and the cop presumed they were just passing civilians and told them to leave. Lois then smiled and stamped on Corben's foot.
Corben later went to his desk opposite Lois' and began squeaking his chair and Lois thought it was Clark but saw Corben and still thought he was a detective but Corben revealed himself as a field reporter to replace Clark. Lois says that Clark will be back but Corben says he is on indefinite leave and shakes Lois' hand before leaving.
One night Corben was covering a story that involved the Blur and after talking with Lois and discussing his plans to expose the Blur for what he really is, he was run over by a truck. His bloodied body was found by Zod and his soldiers, who used him to try an experiment to regain their powers. Using stolen technology from LuthorCorp, they rebuilt Corben's body and transformed him into a cyborg with a kryptonite heart. He was abandoned in the building where the surgery took place and after waking was confused and afraid by what had happened to him. He was transported to the Metropolis General and attended to by Dr. Hamilton who informed him that the implants were what had kept him alive. In a fit of psychosis, John gets up scared, and discovered that he now had super strength, and escapes leaving an orderly in a coma. His adrenaline level started to rise clouding his mind making it think that what happened was a gift to kill the Blur for what he had done to his sister.
John gazing at his reflection
He attempted to track the Blur using the Daily Planet archives, and there he meets Lois, who gives him her key to the Planet's archives room. Realizing that Corben is the man who ran wild at the hospital earlier in the day before fleeing, Lois goes to a phone booth and speaks to the Blur. However, John realizes that Lois had contact with the Blur and decides to kidnap her to find out what she knew. He takes her to the basement of the building in which he lived and after Lois' refusal to collaborate with him, he sent her flying through a wall. Clark appears at that time and tells John that he regretted what had happened to his sister. Corben refused to accept the apologies, and then Clark set off an electromagnetic pulse grenade and momentarily disabled the cyborg. Corben restarted instantly and prepared to kill Lois.
Corben hit by a E.M.P.
Unable to approach the cyborg because of the radioactivity of the kryptonite, Clark heated a lead plate and slammed it into Corben's chest. Realizing the weakness of the Blur, Corben tried to expose his kryptonite heart by ripping the lead plate from his chest, but in the attempt, the meteorite rock stuck to the plate, leaving Corben without power and shutting him down.
Corben with a lead plate
At a later point, Tess Mercer received an update on Corben, who had apparently been "repaired." However, the operations have left him more machine than man, also leaving no vital signs. Later, when Tess visited Winslow Schott, a mad criminal genius who used to work for Lex, she gave him John's kryptonite heart for him to tinker with in an attempt to see if he could help reboot John's systems.
Corben's medical file.
Later, when it was revealed that Kandorians were experimenting on humans, Clark asked a doctor if there was any of the humans that were experimented on and never found. The only one was John Corben. Later, it was revealed that Tess' scientists were able to correct the adrenal flaw in the Kryptonite matrix, thereby returning Corben to sanity. Seeing him as a potential weapon if the Kryptonians ever turned hostile, they implanted a control chip into the back of his neck that would turn him in to a mindless drone.
Corben saves Lois
Lois infiltrated the base where experiments were being done on red kryptonite just as they were bringing Corben back online. When she was discovered, the scuffle set of an explosion from the red kryptonite, throwing her through the base and down an elevator shaft, only to be caught by the reactivated Corben. Waking up the next morning not remembering how she got home, Lois later found him in the Talon basement. While understandably skeptical after their last encounter, Corben assured her he was now sane and he had saved her the previous night. He explained to her about Tess' experiments and the control chip but also that his artificial heart was nearly out of energy and unless he replenished it soon with more meteor rock, it would deactivate and effectively kill him.
Corben at full power
Taking him to one of Chloe's weapon stashes, Corben was able to recharge the Kryptonite matrix with liquid meteor rock. He then encountered Clark (who was under the influence of red kryptonite) but before anything could happen, Zod blew the truck up with his heat vision. He survived and Lois found him nearby unharmed, having been blown from the wreckage. Deciding it was best to get him somewhere safe, Lois was prepared to take him over to the Badlands and out of Tess' reach to a doctor she trusted. Before they could get on the bus, one of Tess' people slipped the control chip onto the port of his neck, instantly taking over his mind. He then returned to the lab, where Tess and Chloe prepared him to stop the Red K infected Clark, who had taken Zod to the Fortress. Chloe, still not trusting Tess deactivated the monitoring system so Tess wouldn't learn the location of the Fortress.
Arriving at the Fortress, he was confronted by Zod and Clark. While he had the advantage due to the Kryptonite Matrix, his lack of free will made it difficult for him to effectively battle the two when they split up. The control chip was knocked loose by debris and his mind restored when Clark used his heat vision to bring down part of the Fortress roof on the cyborg intending to crush him.
John at the Fortress
Coming back to his senses Corben, went straight for Clark again only to be frozen solid by a combination of his and Zod's super breath. This was short lived when they noticed the Matrix began to beat at a faster rate and Corben proceeded to smash his way out of the ice with ease. Being so close to him, they were helpless against the aura of the kryptonite matrix and Corben proceeded to kick Zod into one of the fortress walls. Turning his attention back to Clark, he pulled out a krytonite shard he had been given by Chloe, saying he didn't blame Clark for attacking him in the past but someone who cared about Clark sent him to help. Grinning madly, Clark said he didn't need saving, as Corben knelt down next to him saying from experience that sometimes people dont know when they need saving before stabbing Clark with the shard, freeing him from the Red K.
Corben talks with Lois
Now back in the right state of mind, Clark lept backwards carefully, observing the cyborg. Corben picked up the removed control chip so know one could control him again and waved off Clark's suspicion of him by saying Clark could thank him another time. He pulled out the Key to the Fortress and placed it in the console, disappearing in a flash of light.
After that, John met Lois on the streets of Metropolis. She gave him a new Kryptonite heart, this one being powered by Red Kryptonite instead of green. Corben said that he was going to go underground and wanted Lois to come with him. Lois told him that there was someone else in her life (Clark) and that he was the one. After saying their goodbyes, Corben left.
Powers and abilities
Superhuman strength: Has greater than human strength, sometimes able to stand toe-to-toe with several DC super heroes including Superman.
Regeneration: Metallo has been able to, at times, regenerate his body parts and reconfigure them into weapons.
Technormorphing: In few publishings, Corben's shown the ability to physically assimilate or mentally commandeer any and all mechanical forms via force of will. Changing and alternating they're physical shape and form as well as his own for greater combat efficiency.
Kryptonite emission: He can generate kryptonite radiation that can severely damage Superman.
Super stamina: John can't become tired easily thanks to his robotic state.
Superhuman durability: He can sustain high impacts and explosions with little to no damage.
Green Kryptonite heart: His body functions thanks to the Kryptonite heart imlanted by the Kandorians.The same Kryptonite heart that maintains him alive,allows him to unintenionally generate green Kryptonite radiation,which gives him the upper hand whan fighting Kryptonians.
Red Kryptonite heart: At the end of the episode Upgrade, Lois gaves him a Red Kryptonite heart, which is supposed to be more powerful and to have more energy than the green Kryptonite heart.
Gold Kryptonite heart: Int the superhero shorts of the animated series of Justice League Action, Firestorm accidentally changed Corbens Kryptonite heart into Gold Kryptonite which erased his memeory.
Black Kryptonite heart: Int the superhero shorts of the animated series of Justice League Action, another transmutation snaffu on Firestorm's account changed it into good & evil splitting black Kryptonite. Giving superman both Metallo and an Evil Superman to deal with.
Pink Kryptonite heart: Int the superhero shorts of the animated series of Justice League Action, the final mix up by Firestorm was when his heart was changed to Pink Kryptonite which temporarily flipped Superman's gender to female.