Did Superman go back in time

Everyone knows that Superman's one weakness is Kryptonite, an element derived from the debris of his home planet of Krypton that becomes deadly under Earth's yellow sun. But what happens when you take that Kryptonite, and bond it, irrevocably, to someone with a mad-on for the man of steel?

Metallo happens. While he has had several different origins, the basic idea remains the same: John Corben, who is either a con-man or a soldier, depending on which era he's appearing, is either mortally injured or volunteers for an experiment, resulting in mad scientists bonding his body with robotic pieces which are powered by a heart of Kryptonite — and giving him strength that rivals Superman's, and bonding him with the iconic hero's greatest weakness.

While he's most often appeared as a small-time (in comparison) threat, or as another villain's henchman, Metallo has the chops to really go head to head with Superman. After all, what good is incredible strength if you can't even get close to your enemy?

PARASITE

Another character with several varying but closely related origins and identities depending on the time period, Parasite began life as either Raymond Jensen, or in modern incarnations, Rudy Jones, a low-level worker in a laboratory. Thinking that a container hidden in one of the labs in fact contained valuables, he opened it, exposing himself to strange, radioactive material, and becoming the twisted, vampiric Parasite.

Parasite feeds on energy to live. Originally, this was need was only satisfied by the life energy of others, leaving common mortals dead at his touch, but against someone like Superman, Parasite's deadly touch allows him to sap the powers and memories of his victims, making him more deadly every time they come in contact. He also retains knowledge gained from these encounters, so unlike many of Superman's foes, Parasite is actually usually aware of his secret identity.

Parasite is a formidable foe, and his early origin, in which he had a wife and family who he could no longer touch, added an element of pathos necessary for the best villains. Like many of the villains on this list, he starred in his own one-shot as part of DC's Villains Month, seeing the character brought into the New 52.

MONGUL

Mongul was originally the despotic ruler of a brutal alien world — an occupation not uncommon to enemies of Superman — until the citizens rebelled, exiling him into space. He traveled around, attempting to conquer other worlds, until he came across Warworld, an artificial planet that he ruled without question, forcing its inhabitants to do battle in gladiatorial combat. After attempts to turn Earth into another Warworld, Superman and a veritable army of other heroes invaded the planet, deposing Mongul and saving the Earth.