Spider-Man 3 is a 2007 American superhero film based on the Marvel Comics character Spider-Man. Produced by Columbia Pictures, Marvel Entertainment, and Laura Ziskin Productions, and distributed by Sony Pictures Releasing, it was directed by Sam Raimi from a screenplay he co-wrote with his brother Ivan and Alvin Sargent. It is the final installment in Raimi's Spider-Man trilogy (2002–2007), and the sequel to Spider-Man (2002) and Spider-Man 2 (2004). The film stars Tobey Maguire as Peter Parker / Spider-Man, alongside Kirsten Dunst, James Franco, Thomas Haden Church, Topher Grace, Bryce Dallas Howard, James Cromwell, Rosemary Harris, and J. K. Simmons. It also marks the final acting appearance of Cliff Robertson before his retirement from acting in the same year and his subsequent death in 2011. Set a year after the events of Spider-Man 2, the film follows Peter Parker (Maguire) as he prepares for his future with Mary Jane Watson (Dunst), while facing multiple threats: Flint Marko (Church), Uncle Ben's true killer who becomes the Sandman after a freak accident; Harry Osborn (Franco), his former best friend who is now aware of Peter's identity and seeks to avenge his father; an extraterrestrial symbiote that increases his abilities but amplifies his anger and other negative traits; and Eddie Brock (Grace), a rival photographer who becomes the symbiote's second host Venom.

Development of Spider-Man 3 began immediately after the successful release of Spider-Man 2 for a 2007 release. During preproduction, Raimi wanted two villains, Harry Osborn and Sandman. At the request of producer Avi Arad, he added Venom to the list, and the producers also requested the addition of Gwen Stacy. Principal photography for the film began in January 2006 and took place in Los Angeles and Cleveland before moving to New York City from May until July 2006. Additional pick-up shots were made after August and the film wrapped in October 2006. During post-production, Sony Pictures Imageworks created over 900 visual effects shots. Composer Danny Elfman, who had scored the previous installments, decided not to return due to creative differences and conflicts with Raimi during production of the previous film, so Christopher Young composed the score in Elfman's absence. With an estimated production budget of $258–350 million, the film was the most expensive film ever made at the time of its release.

Spider-Man 3 premiered on April 16, 2007, in Tokyo, and was released in the United States in both conventional and IMAX theaters on May 4. The film grossed $895.9 million worldwide, making it the highest-grossing film of the trilogy, the third-highest-grossing film of 2007 and the tenth-highest-grossing film of all time at the time of its release. It was also the highest-grossing Spider-Man film until it was surpassed by Spider-Man: Far From Home in 2019, and Raimi's highest-grossing film until Doctor Strange in the Multiverse of Madness (2022). Unlike the previous installments, Spider-Man 3 received mixed reviews from critics. A sequel, Spider-Man 4, was set to be released in 2011, followed by a Venom spin-off film along with a fifth and sixth installment, but all were canceled.

One year after Otto Octavius's sacrifice, Peter Parker plans to propose to Mary Jane Watson, who has made her Broadway musical debut. In Central Park, a meteorite lands nearby during their date, from which an extraterrestrial symbiote oozes out and follows Peter to his apartment by attaching to his motorbike. Harry Osborn, knowing Peter is Spider-Man, seeks to avenge his father's death. Using Norman's performance-enhancing gas and Green Goblin technology, he battles Peter to an eventual stalemate, developing partial amnesia after falling from his glider. Meanwhile, police pursue escaped convict Flint Marko, who visits his wife and sick daughter before fleeing. He falls into an experimental particle accelerator that fuses his body with the surrounding sand, granting him the ability to control and reform his body into sand, becoming Sandman.

During a festival honoring Spider-Man for saving Gwen Stacy's life, Peter kisses her to please the crowd, angering Mary Jane. Marko then robs an armored truck and escapes after a duel with Spider-Man. Police captain George Stacy, Gwen's father, informs Peter and Aunt May that Marko is Uncle Ben's true killer; the initial suspect was simply Marko's accomplice. While waiting for Marko to emerge from hiding, the symbiote assimilates Peter's suit as he sleeps in it. Peter awakens atop a building, discovering that the symbiote has turned his suit black, enhanced his powers, and heightened his aggression.

Peter battles Marko in a subway. Finding that water weakens him, Peter opens a pipe, turning Marko into mud and washing him away. Peter's new attitude alienates Mary Jane, who kisses Harry and departs regretfully. A hallucination of his father prompts Harry to recover from amnesia and force Mary Jane to break up with Peter. Later, Harry tells Peter that Mary Jane is dating him. Under the symbiote's influence, Peter fights Harry, spitefully claiming his father never loved him. As Peter leaves, Harry throws a pumpkin bomb, which Peter deflects, disfiguring Harry's face.

At the Daily Bugle, Peter exposes rival photographer Eddie Brock, whose fake photos incriminate Spider-Man. Publisher J. Jonah Jameson, outraged at Brock's false photo and having to print a retraction, fires Brock and promotes Peter to staff photographer. Later, Peter brings Gwen to a jazz club where Mary Jane now works, hoping to make her jealous. Upon realizing Peter's true intentions, Gwen apologizes to Mary Jane and leaves. After assaulting the bouncers and accidentally hitting Mary Jane, Peter realizes that the symbiote is corrupting him. Retreating to a church bell tower and discovering that the sound of clanging metal weakens the creature, Peter removes the symbiote. Seeing the event from the pews below, Brock becomes the symbiote's new host and turns into Venom.

Brock locates a still-living Marko and convinces him to join forces to kill Spider-Man. Brock abducts Mary Jane and holds her captive from a web at a construction site, intending to kill her in revenge for Peter ruining him, while Marko keeps the police at bay. After a now-scarred Harry declines to help Peter, Harry's butler reveals that Norman's death was not Spider-Man's fault. While Brock and Marko pin Peter down, Harry arrives to help Peter and save Mary Jane. Brock attempts to impale Peter with Harry's glider, but Harry jumps in and is impaled instead. While remembering the symbiote's weakness, Peter assembles a perimeter of metal pipes to create a sonic attack, weakening it and allowing Peter to separate Brock from the symbiote.