Marclonus was a Twi'lek male who was a colonel in the Fourth Infantry. He had spent ten years as a Hutt's slave messenger, and was forced to wear a shock collar during that time. During the Battle of Corellia he was stationed at the Government District, where he was charged with securing the Republic's position in the western section of the Records and Communication Sector. Unfortunately, the Imperial Guard ambushed his troops and kidnapped several non-Human officers. Marclonus was furious to learn that his men had been placed in shock collars, and enlisted the help of a Republic hero when his commanding officer refused to send him any additional squads. At Marclonus' request, the hero attacked the Imperial Guards and their shocktroopers, freeing the captive officers and driving the Empire out of that sector.
- Star Wars: The Old Republic (First appearance)