Cybernetically enhanced bounty hunter that was enlisted to track down the Millenium Falcon.
Shortly after the battle of Hoth the Millennium Falcon, with Han Solo, Chewbacca, Princess Leia, and C-3PO aboard, is the last to escape Hoth and is being hounded by Imperial Star Destroyers. Darth Vader, a lord of the Sith, wants Solo and anyone else alive to entice Luke Skywalker, the last potential Jedi in the universe, to either turn him to the dark side or kill him. As the Star Destoryers are much more powerful than the Falcon, Solo pilots into an asteroid field. After being forced back out by a giant alien worm the Falcon flies straight at one of the Star Destroyers and attaches itself to the back so their out of sensor range.
With the sudden disappearance of Solo and the Falcon, Vader decides to tighten the noose around them by hiring scum to do what the Empire can't. Among these elite bounty hunters is Dengar who listens to Vader's offer. The only stipulation is that Solo be brought in alive. Dengar started his search in the nearby asteroid field he saw Solo come out of before eventually tracking the Falcon to Bespin. Instead of capturing Solo he finds that Boba Fett has already beaten him to it.
Dengar wears old and worn stormtrooper armor and is actually a cryborg. He isn't a very good bounty hunter but his frequent encounters with Han Solo, as well as being in the right place at the right time, gets him the bounty on Solo when Vader needs it the most.