Spider-Man 3
Peter Parker has begun to feel secure in his life and plans to propose to Mary Jane. While Peter and Mary Jane are on a date, a small meteorite crashes nearby, and an extraterrestrial symbiote attaches itself to Peter's moped. Meanwhile, escaped convict Flint Marko falls into a particle accelerator that fuses his body with the surrounding sand. The result allows him to shape shift at will, becoming the Sandman. Peter's best friend, Harry Osborn, who seeks vengeance for his father's death, which he believes Peter caused, attacks him. During the scuffle, Harry injures his head and suffers from partial amnesia, making him forget his vendetta.
Later, during a festival honoring Spider-Man for saving Gwen Stacy's life, Sandman attempts to rob an armored car, and overpowers Spider-Man. Gwen's father, police officer Captain Stacy, later informs Peter and Aunt May that Marko is the one who killed Ben Parker. A vengeful Peter waits for Marko to strike again. The symbiote bonds with his costume while he is asleep; Peter discovers that not only has his costume changed, but his powers have been enhanced as well. The black suit brings out the more vengeful, insensitive, and arrogant side of Peter's personality, exemplified by a near-lethal attack on Sandman during a battle.
The shift in Peter's personality alienates Mary Jane, whose career is floundering, and she finds solace with Harry. Harry recovers from his amnesia and, urged on by an apparition of his dead father, forces Mary Jane to break up with Peter. After Mary Jane leaves Peter, stating she is in love with another man, Harry meets him at a restaurant and claims to be the other man. Later, Peter finds him at the Osborn mansion. With the help of the black suit, Peter is victorious in a brutal fight, which leaves Harry's face disfigured. Influenced by the suit, Peter exposes and humiliates Eddie Brock, a rival freelance photographer, who has sold fake pictures to The Daily Bugle supposedly showing Spider-Man to be a criminal. Meanwhile, Sandman recovers from his injuries, and swears revenge on Spider-Man.
In an effort to make Mary Jane jealous, Peter brings Gwen to the nightclub where Mary Jane works. He gets into a fight with the club's bouncers and unintentionally shoves Mary Jane to the floor. Peter realizes the symbiote-suit is changing him for the worse. He runs out of the nightclub and goes to a church bell tower to dispose of it. Initially he is unable to remove the suit, but the sound of the church bell weakens the symbiote, enabling Peter to break free. Eddie Brock is at the same church praying for Peter's death when the symbiote falls from the tower and takes over his body. The newly-empowered Eddie finds Sandman and suggests joining forces to destroy Spider-Man.
The pair put Mary Jane in a taxicab and hang it from a gigantic symbiote web. Peter approaches Harry for help, but is turned down. However, Harry learns the truth about his father's death from his butler Bernard, and arrives in time to rescue Peter; they form an alliance against the two villains. As the fight progresses, Eddie attempts to impale Peter with Harry's glider, but Harry jumps in the way and is fatally wounded. Peter recalls how the church bell's toll weakened the symbiote, and frees Eddie from it by clanging several pipes together to make sonic vibrations. Peter throws a pumpkin bomb at the symbiote just as Eddie attempts to rebond with it, causing both to be destroyed in the resulting explosion.
After the battle, Marko recovers and tells Peter that he had no intention of killing Ben Parker, and that it was an accident born out of a desperate attempt to save his daughter's life. Peter forgives Marko, who dissipates and floats away to his daughter. Peter and Harry forgive each other before Harry dies with Mary Jane and Peter at his side. After Harry's funeral, Peter and Mary Jane begin to mend their relationship.