The Composite Superman is a DC Comics supervillain, an enemy of Superman and Batman. The character first appeared in World's Finest Comics #142 (June 1964) and was created by Edmond Hamilton and Curt Swan.
Fictional character biography
Joseph Meach
Joseph Meach was a diver who had fallen on hard times. In an attempt to draw publicity to himself, Meach set up a water tank on a sidewalk in Metropolis and dove off a building. Unbeknownst to Meach, the tank was leaking and Meach would have died if not for the intervention of Superman. Upon learning of Meach's misfortunes, Superman obtained a job for him at the Superman Museum, where Meach was employed as a janitor. Meach's bitterness did not subside and being surrounded by mementos of Superman's career directed his anger towards Superman. One night, as Meach was sweeping in front of a series of statuettes depicting the Legion of Super-Heroes, a bolt of lightning struck the display. The statuettes (which were actually miniature lifeless duplicates of the Legionnaires) unleashed an energy blast that struck Meach, endowing him with the combined powers of the Legion members. Determined to defeat Superman, Batman, and Robin, Meach used his shapeshifting power to turn his skin green and form a costume that was half of Superman's costume and half of Batman's costume. Calling himself the Composite Superman, Meach left a message in both heroes' bases to meet him on a mountain. There, he told the heroes that if he was not allowed to join their team, he would expose their secret identities, which he had learned via telepathy. The Composite Superman then created situations for Superman or Batman to handle, but which he intentionally sabotaged to humiliate the heroes, then sorted them out himself. Superman and Batman's attempt to expose him by using robot duplicates failed, due to the Composite Superman's ability to read their minds. Just before Meach could reveal the heroes' secret identities, the powers he gained from the statues faded away. Meach tried to write down the secret of his powers in the Superman Museum, but his memory faded before he could finish (though he managed to write down about the lightning striking the statues, but nothing more).
A few years later an alien villain named Xan came to Earth to avenge his dead father, a criminal who had been imprisoned by Superman and Batman. Xan restored Joseph Meach's powers by recreating the original accident. Meach's memories returned and he used the powers of Sun Boy and Lightning Lad to destroy the statues of Superman and Batman, leading to investigation by the duo. This time, the duo were able to deduce their enemy's identity, as they checked the museum employees who were not around when the Composite Superman was sighted. The Composite Superman captured Superman and Batman by impersonating a chained Robin, then tried to kill the team by using his powers to simultaneously turn half of their bodies to anti-matter; Meach's powers wore off before he could accomplish this. Xan appeared and fired a lethal energy blast at the heroes with his Magna-Gun. A remorseful Meach intercepted the blast, dying instantly. A statue was made to honor Joseph Meach, saying that he "lived a villain, but died a hero".
Xan
Xan escaped from prison and traveled back in time to recreate the event that endowed Joseph Meach with his powers, but with himself obtaining the powers. Xan assumed the identity of the Composite Superman and displayed greater control over his powers and understanding over his weaknesses, such as timing his needed restorations of energy to maintain his power. Xan discarded the Composite Superman identity and created an original costume with the new name Amalgamax. Superman traveled to the 30th century to ask the Legion of Super-Heroes for assistance. Superman, Batman, and the Legion defeated Amalgamax by making him believe that the disease that killed his father had developed in him and that his excessive power was causing the disease to develop rapidly.