Eddie Brock a.k.a Venom is the secondary main antagonist of Spider-Man 3; the true main villain is the Symbiote.
Eddie is, at first glance, an exact opposite to Peter Parker in almost every way imaginable--He dresses in spiffy designer clothes, uses enormous hair product, rides a motorcycle and seems progressively tanned.
Eddie is louder, more flamboyant, more able to schmooze and socialize. Eddie is overly arrogant and obnoxious, but certainly a lot more polished. However, Eddie lacks elsewhere, he apparently has no real friends or close family. Eddie considers himself a ladies' man, but the ladies themselves don't concur. He is known to have once dated Gwen Stacy who's a model and a physicist.
But after one coffee date, she has no interest in pursuing things further. Eddie flirts with J. Jonah Jameson's secretary Miss Betty Brant. She's amused at the gesture, but brushes him off. And his cologne seems to disgust more than it attracts. After the alien symbiote took him over, Peter began to act more like Eddie.
After losing his job and his reputation for forging a photo of Spider-Man robbing a bank, Eddie saw Peter with Gwen Stacy and was as depressed as ever. He went into a church and prayed for Peter's death. Almost like a divine hand granted his wish, he heard a scream from above. Peter was at the top of the bell tower attempting to tear the symbiote suit from his body and with the help of the bell's thunderous chimes, the suit seemed to be shrieking in pain. Peter ripped off the symbiote, and as it fell, it landed on Eddie, transforming him into Venom.
Brock, now re-christened and re-born as Venom, traveled around the city web-slinging and swinging in Spider-Man's own style, looking for the real Spider-Man himself. While doing so, he happened to run into the Sandman in an alley. The Sandman attacked Venom, but Venom proposed that the two of them form a partnership against Spider-Man, which the Sandman agreed on.
Brock captured Mary Jane Watson through use of a taxi. Peter put on his old traditional blue and red Spider-Man costume when he heard of her disappearance. Upon arriving at Venom's trap, Peter attempted to plead with Eddie and warned of the dangers of the black symbiote, and the unholy being it made its wearer. The cautions didn't faze Eddie as he preferred being evil. But then Peter's friend Harry Osborn came blazing onto the scene to save Peter, in his New Goblin gear.
Harry tried to keep The Sandman at bay while Peter tried to take care of Venom. Then, Harry sacrificed himself to save Peter and Mary Jane during the ensuing fight, Venom stabbing him with his own glider, similar to how Norman Osborn died.
Peter remembered that it was the loud clanging noise and the vibrations from it that made the symbiote creature scream and grow weak. He took a pipe and banged it against a row of others, making a thundering chiming. Venom writhed in pain, revealing Brock, and Peter ripped Brock from the symbiote. However, the symbiote, now completely independent, prepared to kill the both of them.
Peter grabbed one of Harry's pumpkin bombs and hurled it right at the alien matter. Eddie, seeing what was about to happen, ran toward the symbiote and was caught, and killed, in the explosion.
◾Venom's name was never mentioned in the film.
◾Unlike the other villains, Eddie Brock willingly becomes evil.
◾His working for the Daily Bugle and frame-up of Spider-Man bears similarities to his 1990 counterpart and both get fired as a result but unlike his 1990 he goes to the side of outright evil while his 1990 counterpart redeemed himself and became an ally of Spider-Man.