We don't know much about the hero of The Mandalorian, so there have been tons of theories — including one that he's actually Boba Fett, the villainous bounty hunter who caused problems for the heroes of the original Star Wars trilogy. If you were hoping this theory was true, we have bad news for you: the Mandalorian is not Boba Fett.
The most obvious reason that the helmeted hero is definitely not Boba Fett? The Mandalorian takes place a few years after Return of the Jedi, in which the antagonistic bounty hunter is killed during Luke and company's escape from Jabba the Hutt. Boba Fett is pretty clearly killed without a likely means of escape: his death comes by falling into the maw of the Sarlacc. Being consumed by the Sarlacc is a pretty solid death sentence, and there's no known way out.
Compounding the case for "not Boba Fett" is the fact that Boba Fett is not, actually, a Mandalorian bounty hunter. Attack of the Clones reveals Boba Fett's origins as a clone of a true Mandalorian bounty hunter named Jango Fett. Jango's DNA was the basis for the entire Clone Army, but he raised Boba in particular as his "son," which is why, after his father's death, Boba Fett goes on to become the most feared and ruthless bounty hunter in the galaxy.
"Our guy is a Mandalorian, and we definitely explore the culture of the Mandalorian," Favreau said. Filoni added, "Boba Fett is a clone, according to Attack of the Clones, and by asking [creator George Lucas], he would say Boba Fett is not Mandalorian, not born on Mandalore. He's more of a person indoctrinated into it, into the way of life, and gets a hold of the armor." In a separate interview, star Pedro Pascal revealed the Mandalorian's real name: Dyn Jarren (although that might not be how it's spelled). So although it may be disappointing to fans who were hoping to get a Boba Fett-centered series, The Mandalorian is definitely not it.