One of Spider-Man's oldest enemies, MacGargan has recently abandoned his Scorpion suit and identity bonding with the alien symbiote that had previously been hosted by Peter Parker and Eddie Brock. He now goes by the infamous name, Venom.
Former private investigator Mac Gargan was hired by J. Jonah Jameson to find out how Peter Parker is able to get incredible pictures of Spider-Man. Gargan's efforts to locate Peter in order to find out the truth triggered Parkers's spider sense, making him easily avoidable.
Frustrated, Jameson decided to pay $10,000 to Gargan as the subject of an experiment. An experiment created by Dr. Farley Stillwell, a researcher in animal mutation which endowed the subject with the characteristic of another animal. Unfortunately the process resulted in the loss of Gargan's sanity, and the creation of the super-powered criminal menace known as the Scorpion.
Over the years Scorpion fought and was bested by Spider-Man many times. Most of these confrontations were the result of Spider-Man stepping in on an attempt on the life of Jameson, who Gargan hated even more than Spider-Man. With his mechanical tail, speed, and strength, Scorpion has always been more than a match for Spider-Man. Only the skill, experience, and quick wit of the web head helped him defeat Gargan.
Later on, Scorpion was recruited by Norman Osborn, informed of Spider-man's real identity, and ordered to kidnap Peter's Aunt May if anything should happen to Osborn. In the middle of his task Scorpion was approached by the recently freed symbiote. Risking Osborn's wrath, Gargan chose the symbiote over Osborn's mission, since the symbiote's potential for power was far greater than any newly designed Scorpion suit could ever be. Thus transforming Scorpion into the even more monstrous Venom.
Dying of cancer, Eddie Brock decided to auction for charity to the highest bidder the alien symbiote from which he derives his powers as Venom.
After being purchased by New York mobster Don Fortunato to be used by his son Angelo, thinking him weak, the alien symbiote abandoned its new host leaving him to fall to his death after a short and murderous career.
It then sought out a new host that shared both its hatred of Spider-Man as well as the will and experience of a seasoned criminal. Mac Gargan returned to his apartment after a recent kidnapping of Aunt May and intimidation of Spider-Man, only to find the symbiote which made Gargan a proposition to be its newest host. The one-time Scorpion eagerly accepted the offer, and was thus transformed into the monstrous Venom.
After an elaborate plan paid off and the Green Goblin was out of prison, the Goblin led Spider-Man and the Black Cat into a direct confrontation with the newly formed Sinister Twelve, which included the new, more powerful Venom among its ranks.
In the midst of the battle Osborn escaped, with the full intention to murder Peter's wife, Mary Jane. Spider-Man soon followed only to be stopped by Venom. The two foes continued to battle high above on New York's rooftops. After catching Gargan off balance Spider-Man dropped a condemned building on the new Venom, ending the battle. Venom was arrested and sent to Ryker's. He promised Spider-Man he would never reveal his identity, as that was his only leverage against him.
More recently, Gargan has escaped prison. He journeyed to Battleworld, along with a ragtag group of characters including the likes of Henry Pym, Gravity, the Hood, and others, in order to enter a contest arranged by the Stranger posing as the Beyonder. Shortly thereafter, Venom was approached by a joint CSA / S.H.I.E.L.D. task force, and joined the new Thunderbolts team which was formed during the Civil War to stop unregistered heroes.
Following his stint with the Thunderbolts, Venom was given the opportunity to pose as his hated enemy, Spider-Man, for Norman Osborn's Avengers. As the wall-crawler, Venom had been given the run of the town, disguising his insanity by bringing others to justice and being declared the hero. One such individual saw through Venom's facade and wanted to rehabilitate the evil within him. The Redeemer gathered together a group of others who had come into contact with Venom - leaving them horribly disfigured - and they tried to confront the madman. Venom made quick work of the Redeemer and his gang, leaving some dead and the rest incarcerated. During that time, Osborn had even sent Bullseye and Daken to eliminate Venom for becoming more trouble than he was worth. When they failed, Venom resumed his spot on the Avengers - knowing the next time he was deemed expendable, he would deal with Osborn himself.