Julia Carpenter is a superhero appearing in American comic books published by Marvel Comics. Created by Jim Shooter and Mike Zeck, the character first appeared in Secret Wars #6 (October 1984). Julia Carpenter was known as the second Spider-Woman, later as the second Arachne, and then as the second Madame Web.

Julia Carpenter as Spider-Woman appears in Spider-Man: Across the Spider-Verse (2023), and the Sony's Spider-Man Universe (SSU) film Madame Web (2024) under her maiden name Julia Cornwall, portrayed by Sydney Sweeney.

As Spider-Woman, the character debuted in issue 6 of the first Secret Wars limited series in 1984. She was among the villains and was unknown to all other characters. Since that series, she has appeared as a starring character in Avengers West Coast and Force Works as well as a supporting character in the third Spider-Woman series, whose main character was Mattie Franklin. Julia starred in her own four-part Spider-Woman miniseries which explained her origin and the origin of her enemies, Death Web.

A secretive government group called The Commission decided to create their own superhero. Val Cooper met college friend Julia Carpenter in Julia's hometown of Denver, and convinced her to be part of an "athletic study." She was unknowingly a test subject in their experiments. During the experiment, they "accidentally" injected Julia with a mix of spider venom and exotic plant extracts, which gave Julia powers very similar to those of Spider-Man.

Not long after she was given the identity of Spider-Woman, she was drawn into the first Secret Wars, where she met Spider-Man and the Avengers for the first time, and allied herself with the superhuman champions. She battled the Absorbing Man, Doctor Doom, and the Hulk. She was killed and resurrected by Doom with the power of the Beyonder. After returning to Earth, Julia joined Freedom Force (a government-sponsored super team made up primarily of former members of the Brotherhood of Evil Mutants who enlisted into government service to avoid prison terms). In an early mission with Freedom Force, the team was sent to arrest the X-Men. During this conflict with the X-Men, Julia also began to question her teammates' exceedingly brutal attitudes that they held over from their criminal pasts. Subsequently, Freedom Force was sent to arrest the Avengers after a disgruntled Quicksilver made false accusations against them. Freedom Force actually defeated the combined East and West Coast Avengers teams and helped bring the Avengers into custody at the Vault without a trial. Spider-Woman once again found her loyalties divided; she had a change of heart and eventually chose to break into the Vault and freeing them, battling the Guardsmen and thus becoming a fugitive from the law herself. Alongside Spider-Man, she battled the Wrecking Crew as a government assignment. In another adventure she teamed with Iron Man to battle renegade A.I.M. agents named the Seekers, who sought to capture Valerie Cooper doing undercover solo work. In gratitude for her earlier assistance with the Avengers, Iron Man worked with the government to get her pardoned.

Later, one of her assignments led her to California looking for a team of Asian supervillains called the Pacific Overlords. She met and assisted the Avengers West Coast against the Pacific Overlords and battled U.S. Agent. She was eventually offered membership, joining the Avengers West Coast. As a member, Julia battled some of the Marvel Universe's major foes including Doctor Demonicus, Ultron and Mephisto as well as participating in the Infinity War cosmic crossover. In addition while still a member of the West Coast Avengers, Julia was chosen by Doctor Strange to be a founding member of the Secret Defenders in their first mission alongside Darkhawk (whom she would later recommend for West Coast Avengers membership), Wolverine and Nomad. When the West Coast Avengers disbanded, Julia joined their spin-off team Force Works, whose primary enemies included the alien Kree and long time Iron Man foe the Mandarin. She had a relationship with Moonraker during this time.

Julia's main enemies in her solo adventures were the arachnid-based team called Death Web, which consisted of three supervillains who were created by The Commission, using a variation of the same serum which transformed Julia. When Mike Clemson, founder of Death Web, captured Spider-Woman's daughter Rachel, he blackmailed her into fighting Spider-Man. Even though she nearly killed Spider-Man, she would not commit an act of murder, and Spider-Man helped her rescue Rachel. Eventually, Julia walked away from the superhero business to concentrate on raising her daughter. Like Jessica Drew (the original Spider-Woman), Julia was attacked by Charlotte Witter and had her powers stolen. After the loss of her superpowers, Julia returned to the life of a normal mother.

Julia reappeared in a story arc of the 2006 Ms. Marvel series, using the codename Arachne (which she intended to use). Her powers have clearly been restored. During Civil War, Julia registers under the Superhuman Registration Act, and she and Wonder Man aid Ms. Marvel in the training of novice superheroes.