Hanharr was raised on the Wookiee homeworld of Kashyyyk, living in the canopies with other Wookiees, but never truly feeling at home among them. Instead, he began to take an interest in the Shadowlands, the ground level of Kashyyyk, at an early age, sensing fascination at its perils and constant darkness. To live in the Shadowlands was considered dishonorable by the Wookiees, but the call proved too strong for Hanharr to resist, and he began to spend more and more time there, moving freely and killing at will. In time, his tribe refused to accept him back, for they sensed too much of a killer within him.
When the humans of Czerka Coroperations arrived on Kashyyyk, they didn't immediately seem to pose a threat to the Wookiee tribe. Yet when they had been accepted by Hanharr's tribe and infested it deep enough, they struck against the villagers. Hanharr watched it all from afar, seeing that the humans of Czerka were physically weak but still predators, and knowing that his tribe was about to become enslaved forever, hunted as prey and demeaned. And so, to save them from this cruel fate, Hanharr took it upon himself to slaughter his entire village, starting with the youngest. With two ryyk blades and bowcaster, Hanharr worked his way from the weakest to the strongest of his people, ambushing them in their sleep. When others were awakened by the attacks, he killed them too—but for everyone that died, he grabbed them by the throat and stared into their eyes, showing them the full darkness of the Shadowlands and that their weakness was the reason they had to die. When the Czerka slavers discovered that their herd had been destroyed, they took Hanharr and shackled him, taking him into slavery and intending him to haul cargo on board starships. However, on the ship, there was nowhere for the humans to run when Hanharr set about killing all of them. Over the course of weeks, Hanharr stalked the slavers across the ship, letting them hide and starve slowly, waiting till the last possible moment before killing them, stuffing their bodies into storage compartments as a surprise for the other slavers to find. After all the slavers were killed, the ship—apparently on autopilot—eventually reached its destination: Nar Shaddaa.
Nar Shaddaa was not the worst possible place for a Wookiee hunter to be stranded on. There, Hanharr could again climb to great heights, hunt for prey, and admire the newfound depths of the Shadowlands. Hanharr, having learned Czerka's lesson, decided to take that lesson back to humans, in retribution for his dead people in a twisted version of the Wookiee life debt. He became a slaver, selling entire families at a time, intending to bring about the misery and death of every single human in the galaxy.
There was a bitter history between Hanharr and the human female bounty hunter Mira. Previously, Hanharr had been employed to hunt Mira, and had trapped her in a series of vents, where he planned to ambush her. However, she escaped from him when his own explosives (set to kill her) exploded as he ran after her. He painfully experienced that Mira had broadcasted a signal to temporarily blind the mines' sensor receptors. He was almost killed but, taken by pity, Mira saved his life. It is unknown whether Mira knew she would then be owed a life debt, and it is certain that she wasn't keen on the idea, but Hanharr disliked it even more so. To be shown mercy by prey such as Mira was the worst insult imaginable to the Wookiee, and worse yet, he now owed his life to a human. To Hanharr, Mira had done to him just what Czerka had done to his people—she had broken him with slavery.
He detested the idea of a life debt, because he thought that it made him weak and a slave, yet he held on to this tradition because it was the last thing to connect him to his dead people. He served his life debt to Mira, but believed that by killing her he could free himself; thus he would often swing between wanting to kill her and stalking her from the shadows. At one time, he grabbed her by the throat and promised to derive pleasure from killing her sometime in the future, when the time was right. Mira often told Hanharr that she didn't want his life debt but Hanharr's insanity meant that he could see no way out other than to kill Mira.
As a Bounty Hunter
Hanharr was hired by Vogga the Hutt to meet Goto and kill him. "Goto" always appeared as a hologram, and so no one knew that it was actually the spherical droid projecting it. Vogga warned him to finish the job or not come back to him at all. Working with one of Goto's men, the Quarren Crime Lord Visquis, they planned to capture Jedi Knight Meetra Surik and bring her to Goto for Hanharr to kill. However, Mira came in her place.
Eventually, Hanharr and Mira dueled in Visquis's secret base, and there Mira defeated him. Shortly after, Kreia healed his most serious wounds, saving his life, cursing him with another life debt that Hanharr had no choice but to accept. Hanharr claimed that Kreia honored him by showing him no mercy when she took him to the wastelands of Malachor V to challenge Mira after Surik arrived.
After Surik had entered the Trayus Academy to find and stop Kreia and Sion, Mira, alone, encountered Hanharr on the planet's dead surface outside the Trayus Academy and the two fought each other again in their final duel and Mira won again. Defeated, Hanharr was finished off and killed by Mira, ending his misery and his life debt.