24. Darth Vader
Boba Fett was one of the most skilled and active bounty hunters at the time of the original trilogy, and he was hired on more than one occasion by Darth Vader. Vader hired him to find the pilot who destroyed the Death Star. Boba Fett tracked the pilot, who we, of course, know as Luke Skywalker, to Tatooine where the two had a confrontation that Luke walked away from. Boba shared this news with Vader, revealing to Vader that the pilot was actually his son, whom he never knew had been born and assumed had died with Padme.
In The Empire Strikes Back, Vader hired Boba to track down Han Solo and the Millennium Falcon in order to find Luke and try to turn him to the dark side. Clearly, Boba Fett was someone Vader found useful. He wasn’t the only bounty hunter Vader used, but he proved to be more instrumental than all the others.
The appearance of Darth Vader in any Star Wars story is always exciting, as evidenced by the announcements that Vader would appear both in the Obi-Wan and Ahsoka Disney+ series, so even a brief appearance by the character in a Boba Fett flashback would be fun to see in The Book of Boba Fett.