The Kerestians were a species of humanoids, best known for their mastery of a unique weapon called the darkstick. They were descended from mammalian carnivores on the planet Kerest.
Kerestians were easily recognized by their height and a row of breather tubes that ran along their cheekbones. The breather tubes were once used for long-range, high-frequency communication, but that ability was lost over time. Two thin strips of hair grew in a strange double widow's peak from the ridges, and the strips continued down the Kerestian's back. Their nose was defined by a single, vertical slit above their mouth. Their small ears were little more than holes located at the base of the skull, and were surrounded by folds of skin.
At one point, they had developed a sophisticated civilization, complete with fusion technology and sublight space travel. However, disaster struck when their variable sun went into an inactive cycle. The sun's power was greatly reduced, and the amount of light and heat reaching Kerest was greatly diminished. Temperatures plunged, and the glaciers advanced to cover all of Kerest save a thin band around the equator. Their civilization descended into barbarism. The surviving Kerestians became aggressive, determined hunters, even killing one another without remorse if necessary to survive. Kerestians hunted each other so frequently that a female could never be certain if an approaching male was looking for a mate or for prey. Over the centuries, the Kerestian species approached extinction.
Eventually, explorers working for the House of Tagge discovered the Kerestians. They offered a handful of Kerestian warriors passage off their dying world in return for service as assassins. Word of the Kerestians eventually leaked out to the rest of the Galaxy. Some Kerestians joined the ranks of the Mandalorians. During the Imperial era, many Kerestians became servants of Imperial nobles. Others became mercenaries or bounty hunters working for a variety of criminal and legitimate groups. Some, angered by the Empire's exploitation of their people, even joined the Rebel Alliance.
One Kerestian who resisted the Empire was Nariss Siv Loqesh. An effective bounty hunter, Darth Vader offered him the bounty on Han Solo but he refused. In response to this snub, the Empire placed a 25,000 credit bounty for his capture. This forced Loqesh to disappear for a year and a half, until he resurfaced under the alias of "Andov Syn". He continued in the same vein of work, including a notorious incident on Adim where he eliminated the six mercenaries hired to guard the town.
A contrasting approach was taken by bounty hunter Galasett. He preferred hunting down those that broke Imperial laws, often receiving fines for the excessive damage he inflicted on his victims. Another infamous Kerestian was Limna Yith, a one-time member of the the criminal organization Black Sun. Working on Yen-2, she eventually sabotaged Black Sun's operation there and was forced to flee the planet.
Later this same period, the Kerestian Pormfil worked in the fringe as an engineer onboard the Wild Karrde, the flagship of information broker Talon Karrde.
Not all Kerestians of the Imperial era were from Kerest. Before their civilization collapsed, several sublight colony ships were launched. These starships traveled slowly, taking millennia to reach nearby star systems. A few were recovered in deep space. The Kerestians on board, when taken out of cryogenic suspension, proved to be a highly civilized and disciplined people, quite different from their savage cousins.