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Writer Robert Bernstein and artist Al Plastino created Metallo, the Man with the Kryptonite Heart, for Action Comics #259 (1959), the same issue that debuted the Silver Age (1956–1969) Supergirl. “The Menace of Metallo” opens with unethical journalist John Corben—a dead ringer for Superman (except for Corben's mustache)—gloating as he drives away after committing a murder he staged to appear as a suicide. Critically wounded in an automobile accident, Corben is discovered by motorist Professor Vale. The scientist rebuilds Corben's crushed body and skeleton using a durable, uranium-empowered metal that also gives the rogue tremendous strength. The unstoppable Corben steals uranium from research facilities, hospitals, and a U.S. Army base, and the press dubs him “Metallo, the Metal Man.” Metallo's discovery that kryptonite—the radioactive mineral lethal to Superman—augments his mechanical power allows him to hold the Man of Steel at bay. The villain ultimately errs by mistakenly inserting into his chest a piece of artificial kryptonite—without the ore's radiation, Metallo suffers the equivalent of a fatal heart attack. Corben's embittered brother Roger became Metallo II in Superman vol. 1 #310 (1977), blaming the Man of Steel for his sibling's death. Published during a period when Earth's kryptonite had been temporarily eradicated due to a bizarre chain reaction (beginning in Superman #233, 1971), Roger's cybernetic body, constructed by turncoat S.T.A.R. Labs scientist Dr. Albert Michaels (aka the Atomic Skull), was fueled by man-made kryptonite. Superman #310's cover, by artists José Luis Garcia- López and Bob Oksner, presented the new Metallo in what would be the supervillain's signature pose: opening his shirt and chestplate to reveal his kryptonite heart, waylaying the Man of Steel with its deadly beams. Metallo II soon was dressed in a suit of green-and-orange armor, with a Dr. Doom–like face mask. He assaulted Superman on a handful of occasions, and in one offbeat tale—a Batman/Lois Lane team-up in The Brave and the Bold #175 (1981)—brandished a type of manufactured kryptonite that harmed humans. An all-new Metallo appeared in Superman vol. 2 #1 (1987), masterminded by writer/artist John Byrne, following Byrne's continuity-rebooting 1986 Man of Steel miniseries. As in the 1959 version, the contemporary Metallo is John Corben, a two-bit criminal whose entire body (including his head) was mangled in a car crash. Professor Emmett (now given a first name) Vale saved Corben by transplanting Corben's brain into a kryptonite-powered robotic body that looked remarkably like the steel assassin in James Cameron's The Terminator (1984). Fearing that the newly arrived Superman heralded an impending invasion of Kryptonian super-aliens, Vale created Metallo as Earth's first line of defense and mandated that Corben kill the Man of Tomorrow; he instead murdered Vale. The robotic rogue nonetheless encountered Superman, exposing him to kryptonite for the first time. His kryptonite heart able to bring the Man of Steel to his knees, the superstrong Metallo has often proved more than a match for the weakened Superman. Metallo received a more powerful body from the demon Neron in 1995, and in 2000 he was temporarily upgraded to giant-robot proportions thanks to Brainiac 13. Utterly merciless and able to interface with any technology, Metallo can also transform, turning parts of his body into weapons. He can be de-powered by removing his kryptonite heart, or by severing his head from his body, but to do either generally requires that Superman partner with other superpowered heroes. In the story arc “Public Enemies” by writer Jeph Loeb and artist Ed McGuinness, in Superman/ Batman #1–#6 (2003–2004), Batman discovered evidence, later shown to be erroneous, that John Corben was the gunman of Thomas and Martha Wayne, parents of the Dark Knight's alter ego Bruce Wayne. A 2005 Metallo action figure was manufactured by DC Direct as part of a special “Public Enemies” collection (a Metallo action figure by Hasbro, part of a Superman versus Metallo two-pack, preceded this toy in the 1990s). Also in the mid-2000s, Hiro Okamura, the teenage tech-whiz known as Toyman (not to be confused with the rotund supervillain of the same name), claimed that Metallo's body was forged of a “metallo” alloy that was the property of his family. To reclaim his “property,” Okamura transferred John Corben's psychotic mind into a cloned version of his biological body. Despite Corben's physical rebirth, it is unlikely that the threat of the Man with the Kryptonite Heart will remain dormant for long. Metallo has been seen on television on several occasions: in live action on the syndicated Superboy series (1988–1992), with Michael Callan in the role; in frequent appearances in episodes of the WB's animated Superman (1996–2000), voiced by Malcolm McDowell; in the 2003 “Hereafter” episode of the Cartoon Network's Justice League (2001–2004), voiced by Corey Burton; and voiced by McDowell again in Justice League Unlimited (2004–present). Long before Action #252, a different Metalo (note spelling), a criminal scientist in an ultra-powerful battlesuit, tussled with the Golden Age (1938–1954) Superman in World's Finest Comics #6 (1942). Marvel Comics published a story starring its own Metallo, a menace in a giant suit of indestructible armor, in Tales of Suspense #16 (1961); this character is regarded as a prototype for the Marvel superhero Iron Man.