O'Niner, a Clone Sergeant, served the Galactic Republic's Grand Army during the tumultuous Clone Wars. In the year 22 BBY, he commanded a small, relatively inexperienced unit composed of clone troopers stationed at Rishi Station, a Republic military installation on the Rishi Moon. Despite the perceived monotony of their assignment by his troops, O'Niner fully grasped the crucial role Rishi Station played in safeguarding vital Republic space sectors. When Separatist BX-series droid commandos managed to infiltrate the base, O'Niner bravely confronted them despite facing overwhelming odds, ultimately meeting his demise through execution at the hands of the droids.
O'Niner was a clone originating from the genetic template of the bounty hunter Jango Fett. He was created on the planet Kamino specifically to fight for the Galactic Republic's Grand Army throughout the Clone Wars. Early in the conflict against the Confederacy of Independent Systems in 22 BBY, O'Niner held the rank of sergeant, leading a unit consisting of at least seven other clone troopers at Rishi Station, a Republic military outpost situated on the Rishi Moon. This outpost served to monitor and defend important areas of Republic space against potential Separatist incursions, notably the sector encompassing Kamino. The clones under his command were newly trained recruits undertaking their first assignment.
The outpost's isolated location and lack of regular day-to-day combat operations led to frustration among the clone trooper Hevy, who yearned for more engaging missions. After Hevy voiced his discontent to fellow trooper Fives, O'Niner entered the command center and emphasized the outpost's vital function. With his men standing at attention, he informed them that several clone officers were en route for an inspection, requiring them to prepare accordingly. At that moment, a scanner detected an approaching meteor shower. O'Niner promptly ordered the activation of the base's shields. The meteors harmlessly bounced off the shields. Unbeknownst to O'Niner and his unit, several Separatist boarding ships, cloaked within the meteor shower, evaded detection and landed nearby. These ships carried a BX-series droid commandos team who approached the base to launch a surprise attack, initiating it by eliminating the deck officer on duty, CT-327.
O'Niner attempted to contact CT-327 via his comlink to inquire about the meteor activity. When he received no response from the sentry, he dispatched troopers Nub and Droidbait to investigate. The two clones discovered the droids infiltrating the base, but were swiftly killed. O'Niner then grabbed his DC-15A blaster carbine, put on his helmet, and prepared to engage the enemy. He spearheaded the defense of the base, returning fire as the droids attempted to ascend the main staircase into the command center. Taking cover behind a wall, O'Niner instructed the remaining troopers to alert nearby Republic fleets, but the droids had already disabled the communication beacon. O'Niner was subsequently shot in the leg, causing him to fall on the stairs. Ordering the survivors to retreat, O'Niner was killed by a point-blank shot to the chest from the droids.
The Separatists successfully seized control of the base, but failed to prevent four members of O'Niner's unit from escaping: Hevy, Fives, Echo, and Cutup. Rishi eels killed Cutup. The remaining three troopers successfully met up with Clone Commander Cody and Clone Captain Rex, the officers arriving for the inspection. With their assistance, the clones managed to reclaim the base, but they were unable to reactivate the beacon to warn the Republic about the Separatist fleet gathering in the area. Nevertheless, O'Niner's men ultimately foiled the Separatist plan when Hevy sacrificed himself to destroy the base, thereby alerting the Republic fleet to the Separatist threat.
O'Niner was a resolute commander and leader, recognizing the significance of his assignment despite its monotonous nature. He proved to be a competent soldier, readily engaging in combat when the outpost came under attack.
As a human clone derived from Jango Fett, O'Niner stood at a height of 1.83 meters (6 ft) and weighed eighty kilograms. He possessed [brown](/article/color] eyes, tan skin, and black hair that was beginning to turn gray.
O'Niner wore standard, uncustomized Phase I clone trooper armor. His primary weapon was a DC-15A blaster, a standard-issue weapon within the Republic Army. Like all clone troopers, O'Niner had a behavioral modification biochip implanted in his brain at birth by Kaminoan scientists to ensure compliance with specific orders.
O'Niner made his debut appearance in "Rookies," the fifth episode of first season of the animated television series, Star Wars: The Clone Wars. The episode was initially broadcast on October 24, 2008. Although O'Niner's name was not mentioned within the episode itself, his identity was revealed in the series' accompanying Episode Guide on StarWars.com, which was launched concurrently with the episode. As with every clone trooper featured in the series, Dee Bradley Baker provided O'Niner's voice.