Creating a virus to infect Superman and alter his DNA, Lex Luthor managed to infect the Man of Steel by harvesting the virus in a sliver of Kryptonite. Very soon after being activated the virus attempted to take Superman over, but was removed and became the Hybrid. Growing and becoming a large creature that evolved into a monster resembling Superman, the virus became known as the Hybrid, a mixture of Kryptonian DNA and it's own. As it inherited Superman's powers, it also inherited his weaknesses, allowing it to be defeated and sent to a galaxy with a Red Sun to die.
However, the Hybrid managed to live on in Earth as it had infected several ordinary citizens. The Hybrid grouped together this bunch of citizens and again attacked Superman. The Hybrid needed oxygen to survive, so when the collection was dropped in water, the resounding amount of hydrogen managed to break it apart. With this, Superman believed the Hybrid threat to be finished.
Joshua Michael Allen was a delivery boy who ended up getting caught between the battle of Superman and the Hybrid. However, instead of being sucked into the Hybrid, he was given an altered appearance, extraordinary powers but an extreme hunger. Eating energy from people did nothing to stop Allen's pain, forcing him to try and commit suicide. Stopped by Superman, Allen became the Parasite when he realized that Superman's energy could stop his hunger. However, he was defeated and imprisoned in Belle Reve Penitentiary. After breaking out, Parasite joined the Secret Society. Later escaping, the Parasite tried to absorb the psionic energy passed down to Lois Lane by a member of the Twenty. The energy overwhelmed him, causing him to collapse.
As the Hybrid
As the Hybrid, Parasite inherited all of Superman's powers, albeit with a more grotesque appearance. Able to fly and if ever tested, run faster than lightning, the Hybrid was almost a complete carbon copy of Superman. However, as it was a mixture of Kryptonian DNA and its own, the original weaknesses, in addition to Superman's persisted. In addition to being susceptible to Kryptonite and the Red Sun, being an area where oxygen was bonded with an element as hydrogen was potentially fatal.