Let's be real here for a moment. Bounty Hunters in Star Wars: The Old Republic shouldn't be awesome. They're hired goons who lack the discipline required to be a soldier and the chutzpah required to be a true mercenary. At best, they are rogue agents of "justice," working outside the system they never fit into. At worst they are murderous, sleazebag thugs and contract killers. The Sith have the power of the Dark Side, which gives them the authority to be bloodthirsty conquerors. Bounty hunters are just scumbags with guns.
However, Bounty hunters in the Star Wars universe are inherently cool. They've showed up everywhere - in tabletop RPGs, comic books, toys, video games, and basically all the venues one normally finds runaway "cult" icons. Bounty hunters are popular enough that they have been the main focus of two video games: Star Wars: Bounty Hunter and Star Wars: 1313, which previewed at E3 2012.
And the reason bounty hunters are as cool as they are is because of one character who managed to be more of a badass than the story's principle antagonist, despite (or perhaps because of) having only six total lines of dialogue, very limited screentime, and dying a decidedly unheroic death in the third act. Boba Fett has been a fan favorite ever since the 1978 Star Wars Holiday Special, where he first appeared in cartoon form, and the legacy of his dark, brooding charisma continues to this day.
But how did it all come about? What is it about this character that inspires so much awe?
There are a number of different ideas that got distilled into the character of Boba Fett. The principle aspect, though, is that of the bounty hunter - the thief-catcher with a very grey moral viewpoint.
Bounty hunters pop up a lot in "spaghetti westerns," perhaps most notably in the Sergio Leone "Man With No Name" movies starring Clint Eastwood. Lee Van Cleef's character in The Good, the Bad and the Ugly, "Angel Eyes" Setenza, has a lot in common with Boba Fett - he is ruthless, aloof and kind of mysterious, if somewhat more talkative than the Mandalorian. Oddly enough, actor Jeremy Bulloch, the man inside the suit, patterned Fett's swagger after Clint Eastwood's character in that same movie. If you listen very closely when Boba Fett is walking into the dining room in Cloud City to stand next to Vader, you will hear spurs going jingle-jangle-jingle.
In original drafts of the movie, Darth Vader started out as a bounty hunter, but the character evolved from being a mercenary to more of an evil knight. The character of Boba Fett grew out of that original concept, and was brought to the screen during Act II of the original trilogy - the part of the drama where the situation is traditionally darkest for the heroes. The story called for more villains, ones who were just as bad as Vader but were less obvious.
For the look of the character, they went with concept artist Ralph McQuarrie's original design for a suit of "super trooper" armor, but tweaked it to make it look as though it had been cobbled together from scavenged bits, and added some cool little details (like the braided wookiee scalps hanging over his right shoulder, and the deep dent just above the left brow) to make it look more like he was a dangerous rogue.
Fett is essentially the mirror image of Lando Calrissian - Lando is also "morally grey," but he does what he does because he's looking out for the people of Cloud City, and he is clearly conflicted when things go badly. Fett has no moral qualms about what he's doing, and no empathy for the people involved. He's in it to get paid and settle a score.
In SWTOR terms, Boba Fett seems to be a Powertech. The evidence is too slim to narrow down a specific skill tree, but he is only ever seen using one blaster at a time, and the grapple attack and jetpack charge (which suggests at least a few points in Shield Tech) during the skiff battle in Return of the Jedi are both Powertech moves. His old man was clearly a Mercenary - paired pistols and Tracer Missile spam, 'nuff said.
The prequel movies provided some significant details about Fett's origins - he is a clone, created from the same source - a bounty hunter named Jango Fett - as the Republic's massive Clone Army. While the clone troopers were conditioned for absolute loyalty and military discipline, Jango raised his unmodified clone in a much different way as a son. When Jango was killed by Mace Windu on Geonosis, young Boba carried on his legacy.
The backstory is good to know, but it's not the legacy that makes Boba Fett as popular as he is. The legacy only came about because he proved to be so popular already. Boba Fett got way more attention in the Expanded Universe than characters that got much more screentime than he did.
And it's not his occupation either - Star Wars bounty hunters are not a glorious lot.
If you really think about it honestly, all of the bounty hunters you see in the movies are pretty terrible at what they do.
Zam Wesell works for Jango Fett. She's a half-decent speeder pilot, but not a great shot, and she is clearly a bad judge of character. She fails to assassinate Padme Amidala, fails to elude capture after the screw-up despite being able to change her appearance at will, and fails to realize that her employer values discretion more than he values her life. She dies from a poisoned dart to the throat.
Jango Fett is a bit better than that. He goes toe-to-toe against Obi Wan Kenobi - by then a Jedi Master - and manages to escape. However, his pursuit of Kenobi through the asteroid field shortly after is kind of sloppy - he simply assumes that the Jedi's ship was destroyed in the seismic charge blast and takes off to Geonosis. No scanning for ship debris, no waiting and watching, no making sure the job is done. He is eventually beheaded by Mace Windu, and though you can hardly fault the man for that, you kinda have to wonder by then if he ever took any jobs he succeeded at.
The first bounty hunter we meet in the original trilogy is Greedo, in Episode IV: A New Hope, who almost immediately meets a bad end against Han Solo. In the original version, he's just plain old not bright, failing to realize that Han is drawing a blaster underneath the table. In the Special Edition, he's possibly the worst shot in the galaxy - he's sitting there pointing the gun at Han's face for several minutes before he fires a shot, and it's a clean miss.
The next batch of bounty hunters appears in Episode V: the Empire Strikes Back. Han makes passing mention of a bounty hunter he eluded on Ord Mantell, and later on we see a group of them on board the Executor, receiving instructions from Darth Vader. Boba Fett is the clear winner of this lot, successfully tracking Han Solo to Bespin and claiming his prize. Of the rest of that group, only Dengar makes a second appearance (a very brief, almost unnoticeable background cameo in Jabba's palace in Return of the Jedi). Bossk and Zuckuss simply disappear and are never seen again. IG-88 and 4LOM both make a repeat appearance - as scrap metal in the Ugnaughts' recycling room in Cloud City.
The biggest failure of all comes from Episode VI: Return of the Jedi - Boba Fett gets knocked into the sarlacc pit during Han's half-blind "Three Stooges" flailing routine, delivering his only two lines in that movie: "What the - " and "Aaauugghh!"
So clearly, Boba Fett's enduring appeal does not come from his job. Evidently, he is only slightly less terrible at it than all the other bounty hunters who ever failed to accomplish anything. Which is apparently all of them.
The cool of Boba Fett - and therefore all the bounty hunters that followed - comes from his laconic mystique. He is a man of few words - specifically, fewer than 30 words uttered across 3 movie appearances in the original trilogy. When he does speak, it is blunt and to the point, and he exhibits none of the fear that other men show when speaking to Darth Vader.
He's a mystery wrapped in an enigma. You never know what's going on behind that blank, battered mask, and that makes him intriguing. He is a presence that is "felt" more than simply seen or heard - the way he cradles his blaster carbine, or how he tilts his head ever so slightly, says more about him than more lines of dialogue ever could.
And let's not forget the iconic dented helmet. There's a story behind that big crater above his left brow. Fans debated the origins of the dent for years before it was revealed in Episode II: Attack of the Clones - the helmet belonged to his father, who was bashed by a Reek during the arena battle on Geonosis. Boba repainted the helmet, but kept the dent as a tribute to his father. An alternate story proposes a duel between Boba Fett and Darth Vader - Vader deflects one of Fett's bolts back at him, blasting a crater in his helmet. The "father's helmet" story seems to be the official line, but the "Vader duel" story puts the dent in the correct spot.
The rest of the armor also counts for a bit of his coolness. It's old and beat-up, clearly the mark of a seasoned fighter. It has a bunch of mysterious gizmos all over it, but those are really only implied in the movies. The only gizmos we see him using are his wrist-mounted grappler and the jetpack - the device that ultimately dooms him to the sarlacc's stomach. On the other hand, it is because of the armor and attachments that he is able to eventually escape the sarlacc's stomach in the Expanded Universe.
The reason George Lucas himself didn't add a shot of Fett crawling out of the sarlacc pit was that he didn't want to derail the movie. He had to relieve the character of any further story responsibilities and remove the threat that he represented so that he could get back to focusing on the story of Luke Skywalker and Darth Vader. Boba Fett's salvation was left to the Expanded Universe, which happened in the Dark Empire comic series.
So that seems to be the secret of the bounty hunter's success: an enigmatic badass in awesome beat-up armor. It's a simple enough formula that works, and in the case of Boba Fett, turns an also-ran into a cult icon and the poster-boy for one of the best character classes in SWTOR.