Sydney Sweeney as Julia Carpenter/Spider-Woman

Julia Carpenter is the second hero to use the Spider-Woman mantle after Jessica Drew—who lost her powers briefly after a time-traveling scrap with Morgan Le Fey. Recruited by her friend and governmental girlboss Val Cooper—long-time frenemy of Marvel’s mutants and a generally shady federal agent over her long career—and the secret government group the Commission under the pretense of an athletic study, Julia was injected with a serum of spider venoms that gave her powers resembling those of Spider-Man. Almost immediately drafted into the events of Secret Wars, over her heroic career she’s been a member of Val and Mystique’s Freedom Force, Force Works, an ally of the West Coast Avengers, and like every good superhero has occasionally gone through a bit of depowering herself, before Getting Btter.
And yes, Julia is currently the Madame Web of the comics universe, having been given Cassandra’s powers during Grim Hunt. It’s actually her look as Madame Web that the movie’s version of Cassandra is largely inspired by.