Boba Fett is an unaltered clone of the bounty hunter Jango Fett, raised on Kamino as his son. He appears in The Empire Strikes Back (1980) and Return of the Jedi (1983), his origin is given in Attack of the Clones (2002), and he headlines The Book of Boba Fett (2021).
A character built by absence
In the original trilogy he has almost nothing to do. He tracks the Millennium Falcon to Bespin, collects Han Solo, and falls into a sarlacc. The reputation came from the armour, from the fact that Darth Vader speaks to him as a professional rather than a subordinate, and from four decades of writers filling in the silence.
The two continuities disagree
Legends developed him extensively — he survives the sarlacc, becomes Mand'alor, and is a recurring figure in the post-Endor novels. Current canon takes a different route through The Mandalorian and The Book of Boba Fett, in which the survival is the beginning of an attempt to run Tatooine rather than a return to bounty work.
Where to read him
The Legends anthology Tales of the Bounty Hunters (Bantam Spectra, 1996) is the classic starting point, with Daniel Keys Moran's Fett novella as its centrepiece.