During the Great Hyperspace War, Boyle Marcom was a Human male navigation officer in the Sith Empire's navy, serving for many decades. In 5000 BBY, despite his advanced age and declining physical condition, Marcom was chosen by Yaru Korsin, son of Admiral Eldrak Korsin (under whom Marcom had previously served), to pilot the Omen. The mission was to mine and transport Lignan crystals. However, a Jedi attack disrupted the Omen's jump to hyperspace, causing it to crash on an unknown planet. Some of the crew blamed Marcom for the disaster. Following the crash, Devore Korsin, Yaru Korsin's brother, confronted and killed Marcom.
Serving as a helmsman in the Sith Empire's navy, Boyle Marcom was a Human male during the Great Hyperspace War and the years leading up to it. He began his career navigating Sith starships during the reign of Dark Lord of the Sith Marka Ragnos, and continued under his successor, Naga Sadow. When Sadow launched an invasion of the galaxy in 5000 BBY, initiating the Great Hyperspace War, Marcom became a member of the Sith fleet. In that same year, he joined the crew of the Sith dreadnaught Omen as the navigation officer for a mission to mine Lignan crystals on Phaegon III's largest moon and transport them.
Yaru Korsin, the son of admiral Eldrak Korsin, who Marcom had served under previously, commanded the mission. Despite Marcom's age and diminished capabilities, Yaru selected him as helmsman for the Lignan expedition because of his past relationship with the elder Korsin. As the Omen prepared to leave Phaegon III to deliver the crystals to Kirrek, the Jedi attacked both the Omen and its sister ship, the Harbinger. During the battle, Drev Hassin, a Jedi apprentice, intentionally crashed his starfighter into the Harbinger, sacrificing himself. Although Marcom successfully initiated the jump to hyperspace for the Omen, the damaged Harbinger collided with it, knocking it off course. The Omen sustained severe damage from a gravity well in hyperspace, pulling it back into realspace near an uncharted planet. While Marcom struggled to regain control, Devore Korsin, Yaru Korsin's enraged brother and a member of the mining team, confronted him.
Devore was restrained before he could harm Marcom, and the Omen entered the atmosphere of the planet. The impact of the crash threw the frail Marcom around the bridge. Although injured, Marcom survived the crash, which occurred in a mountain range, and managed to make the dangerous journey from the wreckage to the valley below. However, Devore's anger towards Marcom remained. Korsin gathered several miners, confronted Marcom, and blamed him for the crash, while his fellow miners held Marcom back. Marcom attempted to defend himself, but it was futile. The enraged Korsin, fueled by spice, activated his lightsaber and killed Marcom. Marcom's own lightsaber rolled harmlessly to the feet of Yaru Korsin.
Compared to other Sith, Boyle Marcom was known to be mild-mannered and timid, and by the time of the Great Hyperspace War, he was physically weak. He would become frustrated when arguing with someone he considered stubborn or unreasonable, as was the case with Devore Korsin. The fact that he possessed a lightsaber could suggest that he was also sensitive to the Force. Moments before his death, at the hands of Devore Korsin, he was accused of using it to attack first.
John Jackson Miller wrote the eBook Lost Tribe of the Sith: Precipice in 2009, which was the first appearance of Boyle Marcom.