The Hollywood Reporter has reported that James Mangold is set to direct and write the script for the standalone Star Wars film based on the bounty hunter, Boba Fett.
For those who are unaware, Boba Fett is a bounty hunter who made his live-action debut in Star Wars Episode V: The Empire Strikes Back and also made an appearance in the sequel, Star Wars Episode VI: Return of the Jedi. A younger version of Boba Fett made an appearance in Star Wars Episode II: Attack of the Clones and also had a large presence throughout the animated series, Star Wars: The Clone Wars.
This film along with the previously reported film based on Obi-Wan Kenobi are currently early in development so no other details are confirmed at this time so stay tuned for updates.
Source: The Hollywood Reporter