Zarien Kheev was a Zabrak slave master of the Galactic Empire whose defining attribute was his sadistic personality.
He once owned the mercenary Twi'lek Rianna Saren as his personal slave. After she unsuccessfully tried to escape from him, Kheev—in one of his sadistic moments—cut off one of her head-tails. She later tried to escape again, and that time, succeeded. Some time later, he participated in the Death Star project. His primary function was to control a slave production of mirkanite, a material used in construction of turbolasers, on Mustafar. To increase the production, Zarien used the drugs on slaves. However, those drugs needed to be tested. In order to do it, Kheev contacted a Black Sun vigo Slak Sagar, who hijacked an Agricultural research vessel on Alderaan, and tested the new drugs on scientists. But a short time later, Kheev was contacted by Sagar and informed about the mysterious infiltrators. A short time later, the vessel was destroyed. To find those intruders, Kheev even hired Boba Fett. He then departed for Tatooine to oversee the Imperial slave camp there. When he reached it, he was informed that the mining facilty on Mustafar had been also destroyed. On Tatooine he finally met a source of all his troubles—Rianna Saren, his former slave. He tried to kill her by releasing a rancor, but Rianna managed to defeat the beast. Next time they met in the slave camp, Zarien was escorted by stormtroopers. Willing to seek his revenge, he captured Rianna and sent her to Despayre, a current construction site of the Death Star.
Kheev encounters Rianna for the last time
He also headed to Despayre and was on the surface of the planet until it's final moment. Right before the planet's destruction, he encountered the Twi'lek on the landing pad once again, while she was trying to escape. He shot at Zeeo and boarded the shuttle to the Death Star, certain that Rianna would die during the explosion.
After the battle station fired its third superlaser shot, Kheev met with Darth Vader aboard the Death Star. Vader sent him to Danuta with the updated battle station plans, that architects requested. Little did Kheev know that Rianna in fact survived the destruction and even infiltrated the Death Star and heard his conversation with Vader. So when Zarien reached Danuta, the plans that were kept there had been already stolen by Kyle Katarn, after Rianna informed the Rebellion about them. A short time later, she also reached Danuta on a stolen ship. Kheev, however, was not ready to give up without the fight, and met her on a landing pad in his personal battle armor. But he was defeated by the Twi'lek and her droid. Before dying, Zarien managed to fire a last shot at Saren, but it only damaged Zeeo.