Spider-Man (Peter Parker) is a superhero appearing in American comic books published by Marvel Comics. He is a modernized, alternate universe counterpart of Spider-Man who is in his youth, a superhero first created by Stan Lee and Steve Ditko in 1962. The Ultimate version of the character originated in Ultimate Marvel, a line of comic books created in 2000 that is set in a parallel universe with a narrative continuity separate and independent from the main continuity of Marvel Comics stories that began in the 1960s.

Ultimate Spider-Man, the first and flagship title of the Ultimate line, was created by the writer Brian Michael Bendis and artist Mark Bagley, and debuted in September 2000, which featured the first appearance of the Ultimate version of the character. Based on the original Spider-Man who debuted in 1962, he was bitten by a genetically-mutated spider, which gave him superhuman spider-like abilities which led him to become the superhero Spider-Man, and fight crime after the tragedy of his late Uncle Ben. The biggest difference is that this version of Parker is killed at the age of 16, being Spider-Man for a span of almost a year before being replaced by the 13-year-old Miles Morales. However following the Secret Wars storyline, Miles and his family were retconned into the history of the prime universe and Peter who had been resurrected had resumed his superhero role. To differentiate him from other incarnations, Peter Parker from this universe is commonly dubbed Ultimate Spider-Man.

At around the age of six, Peter Parker was orphaned after the death of his parents in a plane crash and was raised by his father's brother, Ben Parker, and his wife May. Nine years later, Peter grew to be an exceptionally bright teen and a high school genius, being particularly skilled in physics and chemistry. However, he was also an introverted outcast among his peers and was frequently bullied and tormented by Fred "Flash" Thompson and Kenny "King Kong" McFarlane. On a school field trip to the scientific corporation Oscorp, he was bitten by a genetically-mutated spider, which gave him spider-like superhuman abilities. The head of Oscorp, Norman Osborn, discovered this and experimented with the same mutagen injected within the spider's bloodstream on himself, but the experiment went awry, mutating him into a monstrous, green-coloured and hulking goblin-like creature later known as the Green Goblin.

After discovering his new abilities, Peter used his powers for personal gain, like his standard counterpart, to financially support his family as a professional wrestler and to become popular by becoming the school's top basketball player thanks to his enhanced spider-powers. However, he began to selfishly utilise his abilities and started to act irresponsibly, which adversely affected his studies and behavior, all of which worried his aunt and uncle. Peter was later fired from his job as a wrestler under suspicions that he was responsible for a recent robbery, much to his chagrin and disappointment. Later that night, as he was walking to his house, he encountered an armed robber escaping from a nearby convenience store, but refused to stop him out of spite and continued to walk home. After returning home and having a heated argument with his aunt and uncle over his failing grades and increasingly reckless nature, Peter ran away from home out of anger. After regretting his argument with his aunt and uncle, he returned home intending to apologise and reveal his spider-powers to them, but upon arriving, he saw a police car and an ambulance parked outside his house, and to his horror, he discovered that Uncle Ben had been murdered by an armed thief. Fueled with rage and a thirst for vengeance, a masked Peter hunted down his uncle's killer. After cornering the criminal within an abandoned warehouse, Peter managed to subdue him and found out, to his shock, that the killer was the same robber whom he refused to stop earlier that night. He then handed over the killer to the arriving police. Guilt-ridden, Peter vowed to follow his uncle's motto, "with great power comes great responsibility", and became the masked vigilante Spider-Man in order to utilise his spider-powers for a noble purpose and to atone for his uncle's death.

In his first year as Spider-Man, Peter encountered the Green Goblin, who later disappeared into the river below the Brooklyn Bridge, following his defeat. Peter Parker later got a job as a web designer for the Daily Bugle upon being hired by J. Jonah Jameson, the snarky and cynical editor of the Daily Bugle, who disliked Spider-Man and constantly ran defamatory smear campaigns against the vigilante. Later, he confessed his identity to his classmate, crush and childhood friend: Mary Jane Watson and they formed a close romantic relationship. Peter Parker later met Gwen Stacy, which initially put pressure on Spider-Man's current relationship with Mary Jane Watson. This issue was later resolved and the three became good friends.

After being defeated by Spider-Man in a sudden reappearance, the Green Goblin was apprehended and incarcerated in the Triskelion alongside Doctor Octopus, Electro, Kraven the Hunter, and Sandman. They escaped from the Triskelion and formed the Ultimate Six. When the Green Goblin threatened to harm Aunt May, Spider-Man reluctantly allied with the Ultimate Six and they attacked the White House. When Captain America confirmed that Aunt May is safe, Spider-Man assisted the Ultimates in fighting the Ultimate Six.

In a later encounter with Nick Fury, Spider-Man learned that Nick Fury learned his secret identity upon finding evidence including footage of the spider that bit Peter Parker and the fact that Doctor Octopus was ranting in his cell about Peter Parker being Spider-Man.

During the "Ultimatum" storyline, Peter and those in his life survived the Ultimatum Wave caused by Magneto where Peter became Spider-Man to help save the drowning civilians. While Spider-Man was doing heroic acts, J. Jonah Jameson started publishing his heroic acts. While working with the Hulk, Spider-Man found the body of Daredevil, who became one of the casualties of the Ultimatum Wave. When the two of them arrived at the ruins of the Sanctum Sanctorum, Spider-Man and the Hulk found a rift open where Dormammu and different demons were emerging at the time when Doctor Strange was possessed by Nightmare. When the Hulk caused an explosion during the fight, Spider-Man was caught in the explosion. Following the death of Magneto, the Ultimates found Spider-Man unconscious while searching for survivors.