Harro Ruuk, a Neimoidian male characterized by both ambition and a propensity for violence, was in the service of the Trade Federation during both the Separatist Crisis and the early stages of the Clone Wars. In the time period two years before the Galactic Republic and the Confederacy of Independent Systems became embroiled in a galaxy-spanning war, Ruuk held the position of commander over droid forces stationed on Maramere within the Karthakk system, having assumed this role after the death of his predecessor, Lord Toat. He pursued the pirate known as Nym to the Haunted Straits with the goal of eliminating the pirate group led by Sol Sixxa.
Ruuk, in his capacity as the Trade Federation Regional Commander for the Karthakk system, was in charge of the military operations against Nym's group, the Lok Revenants. Adi Gallia and Nym sought out Ruuk and his sensor station, which he had been using to track Nym and his crew. When the Lok Revenant forces attacked his sensor station, he escaped using a crab submarine. Though his submarine was destroyed, Ruuk was able to get away using an escape pod.
Soon after, he encountered Captain Cavik Toth and showed him his new bioweapon called trihexalon. Upon learning that the weapon's production was behind schedule, Toth used a sample of the weapon to kill Ruuk and his subordinates.