Claudius Marcus was a native of the planet 892-IV, and the Proconsul of a Roman Empire that had yet to fall in the early modern era. His sphere of influence was unclear, but his power base appeared to be in his civilization's burgeoning television industry.
In 2262, Marcus encountered Captain R.M. Merik of the damaged Federation Merchant Marine survey vessel SS Beagle, and persuaded him to surrender the ship's crew. Survivors willing to assimilate were spared, and the uncooperative ones were sent to fight as gladiators in the televised arena games. The ratings appeal of "barbarians" fighting and dying led to a close alliance with the corrupt and pliant Beagle captain, who consented to lure more exotic ratings fodder.
When three USS Enterprise officers were captured in 2268, Marcus found the starship Captain James T. Kirk to be far more resilient than Merik, and was unable to convince Kirk to surrender his crew. Frustrated, but admiring Kirk's display of manly virtue, Marcus gave his slave Drusilla to Kirk for an evening's pleasure, so Kirk could die "as a man" the next day. Marcus' open contempt for Merik's weak will led to the Enterprise officers' escape. Betrayed by Merik, Marcus killed him by stabbing him in the back. (TOS: "Bread and Circuses")