Spider-Man 3

Peter Parker has begun to feel secure in his life and plans to propose to Mary Jane. One night in a park, while Peter and Mary Jane are on a date, a small meteorite crashes nearby, and an alien symbiote oozes out, attaching itself to Peter's moped. Meanwhile, escaped convict Flint Marko falls into a particle accelerator, which 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. The battle leaves Harry with short-term 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. Captain Stacy later informs Peter and Aunt May that Marko is the one who killed Ben Parker, and 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 also brings out the more vengeful, selfish, and arrogant side of Peter's personality, exemplified by a near lethal attack on Sandman during a battle underground.

The shift in Peter's personality alienates Mary Jane, whose stage 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 MJ 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, Jr., a rival freelance photographer, who has sold fake pictures to The Daily Bugle supposedly showing Spider-Man to be a criminal.

In an effort to make MJ jealous, Peter brings Gwen to the nightclub where Mary Jane works. Peter gets into a fight with the club's bouncers and knocks MJ 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 get rid of it. Initially he is unable to pull the suit off, 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 that they join forces to destroy Spider-Man.

The pair use Mary Jane as bait to force Spider-Man to confront them. 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, teaming up against Brock and Sandman. As the fight progresses, Brock attempts to impale Peter with the glider, but Harry sacrifices himself 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. Peter throws a pumpkin bomb at the symbiote just as Eddie attempts to rebond with it.

After the battle, Marko 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. 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.