Larson is playing Carol Danvers, a skilled test pilot whose DNA is melded with that of Kree warrior Mar-Vell.
There's no word yet on what Law's role will actually be in the film.
In the world of Marvel Comics, Danvers gains her powers after an incident that involves Kree technology exploding and infusing her with the powers of Mar-Vell.
Sources have toldVariety that The Talented Mr. Ripley star is now in negotiations to play Doctor Walter Lawson, otherwise known as Mar-Vell, the Kree Hero who was the original Captain Marvel in the comics. Ben Mendelsohn (Rogue One) is in talks to play the main villain in the film, which is expected to introduce the Skrulls - a shape shifting alien race - into the Marvel Cinematic Universe.
The most recent script was written by Geneva Robertson-Dworet with previous drafts penned by Meg LeFauve and Nicole Perlman. She later adopted the Ms. Marvel and Captain Marvel codenames in his honor. It's also thought that Law will return as Mr. Watson in the third Sherlock Holmes movie with Robert Downey, Jr, although there have been few developments on the continuation of that franchise (which is produced by Fantastic Beasts' Lionel Wigram).
The Fantastic Beasts sequel comes out on November 16, 2018 while Captain Marvel hits theaters on March 8, 2019.More news: Baker Mayfield grabs crotch, shouts expletives at Kansas sideline after TD