Venom (real name Eddie Brock) is a comic book supervillain in the Marvel Comics universe, and an enemy of Spider-Man. He was created by writer David Michelinie and artist Todd McFarlane based on a number of plot ideas and concepts from various other creators. His popularity soared during the 1990s.
While embroiled in a major crossover storyline fighting the Secret Wars on an alien planet, Spider-Man acquired an alien costume. It responded to his thoughts, was able to mimic street clothes and seemed to provide an inexhaustible supply of webbing. Unfortunately, once on Earth, Spider-Man learned that the costume was in fact a sentient symbiote. With the aid of Mister Fantastic, Spider-Man managed to have the costume removed. The costume made one more attempt to bond itself to Spider-Man but was forcibly rejected. Weakened by the rejection, the costume slithered away, presumably to die.
Meanwhile, reporter Eddie Brock had been penning a number of articles on the recent Sin-Eater case. Following a false lead, he proceeded to write a series of columns identifying the wrong man as the perpetrator of the crimes. His mistake was revealed when Spider-Man caught the real criminal. Planning to kill himself, Eddie went to a church, to apologize to God for not being strong enough to handle this life. In that church, Eddie was found by the alien costume, which bonded itself to the failed reporter. The process left both, already emotionally unstable individuals, permanently damaged. Adopting the name Venom, the new symbiotic pair decided to take their revenge on Spider-Man.
It is interesting note that this 'origin' story has been in some ways retconned in order to add depth to the characters involved. It is revealed that Eddie was diagnosed with cancer before the Sin-Eater case, and was told he had little more than 3 months to live. It is this, not the Sin-Eater situation, which finally drove to Eddie to decide to kill himself.
The symbiote's motiviations were also changed. While before it was implieed that it sought Eddie because they were both had a hatred of Peter Parker / Spider Man, but it was revealed that the form of cancer Eddie had come with an enhanced production of adrenaline - exactly what the symbiote feeds off of.
Venom is jet black with a large symbol of a white black widow spider on his chest. He has a gaping mouth filled with razor-sharp teeth, a long, lolling tongue, and is often depicted with drooling a green slime-like substance. He is stronger, faster and more agile than Spider-Man, due to the symbiote's amplification of Brock's own inherent athletic ability. His webbing, which the symbiote generates from the mass of its own body, is more durable than Spider-Man's mechanically-generated webs. The symbiote's shapeshifting ability allows Venom to camouflage himself like a chameleon or to assume the likeness of nearly any person. Venom also has the ability to remain undetected by Spider-Man's spider-sense, making him one of Spider-Man's deadliest foes. However, the symbiote is highly vulnerable to fire and sound.
Despite his lethal ability and homicidal hatred of Spider-Man, Venom remains curiously protective of those he considers innocent. He will generally avoid killing bystanders or innocents in his quest for vengeance if it can be avoided. Of course, the fact that he is insane means that his definition of "innocent" and "necessary casualties" fluctuate as the story demands. He has teamed up with Spider-Man on several occasions, most notably to battle the symbiote's homicidal offspring, Carnage, and has occasionally worked alongside other anti-heroes and superheroes. Since then, however, Venom has on several occasions renewed his quest to see Spider-Man (and, on occasion, Spider-Man's clone, the Scarlet Spider) dead.
Although Brock and the symbiote were thought to have been permanently bonded, the symbiote was recently separated from a cancer-ridden Brock and bonded with a series of people, including the Antarctic researcher Patricia Richardson, the X-Man Wolverine, and the minor criminal Angelo Fortunato.
In the Ultimate Marvel universe, Eddie Brock is Peter Parker's cousin, and the symbiote is not an alien, but the creation of their fathers. Richard Parker intended it to be used for medical purposes, but Brock Sr. was more interested in the military applications. Eddie continued his father's research, and created two symbiotes. One bonded with Peter, leading to a varient of the "alien spider costume" storyline. Afterwards he warned Eddie of the dangers of the symbiotes, but Brock nonetheless bonded with the other one, becoming Venom.
Venom has also appeared as a playable character in several video games. He was a playable character in Marvel vs. Capcom and Marvel vs. Capcom 2, in which he was known for his "Venom Web" finisher as well as his moves that had great range. He also appeared in the Spider-Man game Spider-Man: Maximum Carnage and starred in Venom: Separation Anxiety, both of which were based on actual comic book plotlines.