Lets start with the obvious choice and the one he’s been linked to. The fan favorite option for Morrison to play is that of the infamous bounty hunter Boba Fett.
Famously, Fett’s last canonical appearance was in Return of the Jedi, when fell into the Sarlacc Pit during Luke Skywalker’s rescue and escape of Han Solo from Jabba the Hutt’s barge on Tatooine.
Fett was presumed dead after being eaten by the Sarlacc, However, there are numerous stories of him escaping in Star Wars Legends, and there are various fan theories stating that he possibly survived and escaped from the Sarlacc in current canon.
To further support this idea, Fett may have already appeared in The Mandalorian, albeit from his waist down.
In Season 1 Chapter 5: The Gunslinger, Mando pursuits a target on Tatooine with another young bounty hunter. The target ends up being killed and her body left in the desert, but at the end of the episode, a mysterious figure is shown walking up to her body from the waist down, and Fett’s trademarked boot spurs can be heard.
Seeing as Fett is also a famous bounty hunter, and Tatooine is the planet he was last seen on five years prior to the show, and similar boot spurs’ clanking can be heard, it appears Jon Favreau is very heavily teasing that he did escape from the Sarlacc and was back at work tracking a bounty.
Factor in all that and Morrison’s casting in the show, it appears all but official that Boba will make his return to a live action medium in Season 2.