Marrt was a clone trooper sergeant in the Grand Army of the Republic's 182nd Legion. During the first years of the Clone Wars, Marrt and a squad of three clone troopers—Chatter, Recon, and Knuckles—were sent to the planet Belgaroth on a reconnaissance mission to check a local Republic factory suspected of selling arms to the Confederacy of Independent Systems, the Republic's enemy in the war. The factory was operated by Czerka, a corporation specializing in weaponry. Once on Belgaroth, Marrt discovered that the head of the facility, Tarin, was secretly dealing with representative Reep Tonith of the InterGalactic Banking Clan, which was connected to the Confederacy.
During the course of the mission, the three other men in Marrt's squad were killed by a droidbreaker, a creature indigenous to Belgaroth. The sergeant, however, managed to take Tarin into custody, obtained valuable evidence from the facility, and then burned it to the ground. Weeks later, while he was recovering on Sacorria from the injuries he had sustained on Belgaroth, Marrt requested a Jedi Order representative to come visit him in his medical facility. When Jedi Master Kit Fisto and Padawan Ahsoka Tano arrived at the facility, Marrt handed them the evidence that he had extracted from the Czerka factory, an act that helped Fisto expose two senators who had been profiting from deals with the Confederacy.
Marrt was the nickname of one of many clones produced from the bounty hunter Jango Fett's DNA and bred on the planet Kamino to fight in the Grand Army of the Republic. By the time of the first two years of the Clone Wars, Marrt served as a sergeant with the 182nd Legion, as the war between the Galactic Republic and the Confederacy of Independent Systems raged throughout the galaxy. During this time, rumors spread that a Republic-affiliated factory run by the Czerka corporation on the planet Belgaroth was secretly trading with the Confederacy. Marrt, along with a scout squad of three clone troopers—Chatter, Recon, and Knuckles—was sent to Belgaroth to investigate those claims. After landing on the planet by dropship and trekking to the factory, the four clone troopers separated; while Marrt proceeded to check the factory, the rest of the squad remained in hiding nearby.
Marrt inspects the cargo of FEX-M3 grenades.
Inside the Czerka factory, Marrt witnessed Tarin, the head of the facility, talking to Reep Tonith of the InterGalactic Banking Clan, an organization with ties to the Confederacy. The two were discussing a shipment of FEX-M3 nerve gas grenades—which had been banned by the Galactic Senate a year earlier—to Confederate Head of State Count Dooku. Tarin had failed to produce the requested amount of grenades and asked Tonith to give him more time, to which the latter grudgingly agreed. Marrt obtained one of the grenades as evidence and attempted to slip back to his men undetected but was spotted by a B1-Series battle droid from Tonith's escort. As the rest of the battle droids opened fire, Marrt ordered a tactical retreat, and the four clone troopers fell back to a foggy swamp.
Chatter tried to contact Republic headquarters, but the fog affected their comlinks, and they were unable to do so. To make matters worse, a sudden screech sounded over the swamp and frightened Knuckles, who suspected that more battle droids had found them. However, Recon, a skilled scout, realized that the sound was emitted by something big that was approaching their way—indeed, a native creature known as a droidbreaker suddenly emerged from the fog and charged at Recon. Marrt shouted at the trooper, telling him to move away, but Recon, unable to react in time, was hit by the droidbreaker and hurled into a tree, dying upon impact. As the creature chewed on Recon's blaster, Chatter frantically fired his own weapon at the creature. He was unable to hit the droidbreaker because of the fog, and Marrt ordered him to cease fire.
The three troopers realized that they were standing in the creature's natural habitat and needed to get out of the swamp. Before they could come up with a plan, the droidbreaker struck again and killed Chatter. In response, Knuckles attacked the creature with his bare hands, but he was unable to inflict any damage to it and told Marrt to hide while he distracted the beast. Knuckles was killed as well, though his distraction gave Marrt precious time to formulate a plan to defeat the droidbreaker. Clenching the stolen nerve grenade in his hands, Marrt scaled a tree, taking position high above the ground on a branch. When the beast prepared to attack him, Marrt threw the grenade at it, and the droidbreaker caught the grenade in its mouth. Marrt then opened fire with his blaster pistol, detonating the grenade and killing the creature instantly.
Marrt buried his fallen squadmates under the droidbreaker's severed head and swore a battle oath: to burn the shipment of nerve grenades before it could be sent off-planet. Marrt single-handedly assaulted the Czerka factory and fought for several hours against Tonith's battle droids, receiving major injuries to his legs during the fight. In the end, he destroyed the droids, shackled Tarin, and burned the facility to the ground, although Tonith escaped in his shuttle. Additionally, fearing that Tarin might not reveal the identity of his superiors, Marrt had obtained Czerka's data records before he set fire to the factory. As he was evacuated from Belgaroth, Marrt kept the data records with him, hoping to deliver them to the Jedi Order personally.
Marrt recovering on Sacorria
Marrt was transported to the clone medical and rehabilitation facility on the planet Sacorria to undergo treatment for his injuries. Meanwhile, the Jedi interrogated Tarin, but the man refused to tell anything to his captors. Three weeks later, Marrt contacted the Jedi Order and requested that Grand Master Yoda send a Jedi to Sacorria. Yoda assigned Master Kit Fisto and Padawan Ahsoka Tano to address the clone's request, and the two soon arrived at the medical facility. Marrt told Fisto the story of his mission to Belgaroth and presented him with the extracted data records. Checking them, Fisto discovered that two influential senators were responsible for selling arms to the enemy. Fisto and Tano promised to deal with the traitors and commended Marrt on his bravery. They then left Sacorria and let the soldier continue his recovery.
Marrt was deeply affected by the loss of his squad on Belgaroth and swore to carry out the mission alone after their deaths. He believed that Knuckles' attempt to distract the droidbreaker was brave and thought that it was only thanks to that distraction that he was able to conquer the beast. Marrt was able to complete his mission despite the injuries he had sustained, and he was farsighted enough to extract the data records from the facility before destroying it. Despite being severely injured and weakened during his meeting with the Jedi, Marrt kept a positive attitude, referring to his mission as a "little tale" and behaving sarcastically toward his 2-1B nurse. Fisto considered Marrt's actions on Belgaroth brave and reminded Tano—who had been reluctant to go to Sacorria in the belief that a meeting with some wounded clone was a waste of time—that even the actions of a single soldier could be very important. Like his genetic template, Jango Fett, Marrt stood 1.83 meters tall. He had black hair and blue eyes.
Marrt appeared in A Trooper's Tale, a short comic strip published in Star Wars: The Clone Wars Comic 6.8 in May of 2010. The framing story is set on Sacorria, and Marrt serves as the narrator for the main storyline that depicts the mission on Belgaroth. A Trooper's Tale was written by Robin Etherington and illustrated by Andres Ponce.