Slak Sagar was a Human male, as defined by his gender, who fought for the Galactic Empire throughout the Galactic Civil War.
Leading up to the Battle of Yavin, he acted as the primary enforcer for Zarien Kheev aboard a stolen research ship orbiting the planet of Alderaan.
During this time, his assignment involved conducting trials of an experimental substance, utilizing captured research personnel as test subjects. The objective of this drug was to enhance the productivity of laborers on Mustafar. These workers were extracting mirkanite for the Empire, a component essential in manufacturing turbolasers, which were planned for deployment on the Death Star. When Rianna Saren, a mercenary employed by the Rebel Alliance, breached the research vessel and eliminated the drug supply, Sagar instructed his subordinates to halt operations and vowed to Zarien Kheev that he would locate the infiltrators. He engaged Rianna Saren in combat on a landing pad, where she ultimately killed him. Before departing, Rianna appropriated his heavy blaster pistol for her own use.
Sagar also had a torture droid in his possession, and it defended him during his confrontation with Saren.