Loski was a male Klingon in the 23rd century. By the early part of the century, he had attained the rank of Admiral, and was made military governor of a three-planet star system (later dubbed System Loski) near the Klingon-Federation border.

Due to a number of circumstances in the early days of the war with the Federation, System Loski was cut off from Qo'noS, requiring Loski to resort to unconventional means in carrying out the war. To that end, he authorized a bioengineering project to alter Klingon physiology to more closely resemble humans, allowing them to infiltrate Starfleet ships and facilities.

Despite this project's success, Loski met with fierce opposition, particularly once contact between System Loski and the rest of the Empire was reestablished. Loski was ordered to halt his project, but he refused, leading to a brief civil war between imperial forces and those loyal to Loski. Loski's forces were eventually defeated, and Loski himself died in combat. (TNG short story: "I Am Klingon")

While ENT episodes "Affliction" and "Divergence" appear to contradict much of this story, it is possible that Loski endeavored to recreate the 22nd century mutagen for his own purposes.