Marka Ragnos was a half-breed Dark Lord of the Sith that was immensly powerful, both physically and in the Force. He defeated Simus in combat, proving himself worthy of the mantle of Dark Lord of the Sith. Feared, obeyed, and admired among the Sith, he was known to have been the greatest Dark Lord of the Sith to rule the ancient Sith Empire.

The details of his century-long reign are few, although his death marked the end of the golden age of the Sith Empire, despite his reluctance to continue expansion. Immediately following his funeral, a schism erupted between the leaders of the Sith, and further events led to a major war with the Galactic Republic and, because the schism was never healed, ultimately the end of their interstellar empire.

His death resulted in the rise of another Sith Lord, Naga Sadow, shortly before the Great Hyperspace War. In a twisted perversion of Force Immortality, his spirit was trapped within the confines of his tomb in the Valley of the Dark Lords on Korriban, long after his death.
Recently his tomb was raided, but nobody knows what has been stolen. Rumours speak of a Sith Artifact that is powerful if someone knows how to wield it.