The droid tri-fighter represented a model of droid starfighter that was put to use by the Confederacy of Independent Systems during the period known as the Clone Wars. Its design was specifically geared towards engaging in and dominating intense dogfighting scenarios. Although it was the smallest starship found within both the Republic Navy and the Confederacy navy, this tri-fighter boasted substantial firepower and an advanced droid brain. This advanced intelligence granted it an advantage when facing off against pilots of organic origin. These droid brains surpassed the sophistication of those integrated into other droid starfighters produced for the Confederacy. Envisioned for the complete annihilation of adversaries, it was equipped with a diverse array of missiles and other weaponry.
This tri-fighter proved to be a significant challenge for clone pilots throughout the galactic conflict, participating in key battles such as the Battle of Sullust, the Battle of Dathomir, and the Battle of Coruscant. As the war concluded, the tri-fighters were rendered inoperable when Darth Vader initiated a shutdown command, effectively deactivating all Separatist units that were still active. Even five years after the Clone Wars ended, tri-fighters were observed harassing the newly established Galactic Empire under the control of dissenting groups, including a cell commanded by Berch Teller, a former official of Republic Intelligence.
With a length of 5.4 meters, the standard tri-fighter was the smallest starship in the fleets of both the Separatist and Republic navies. As a space-faring counterpart to the Trade Federation's feared droideka, the tri-fighter's design centered around a single objective: the utter destruction of its opponents. Engineered for high-intensity dogfights and close-quarters space engagements, the tri-fighter, in contrast to Vulture-class starfighters, had more sophisticated brains than standard Separatist droid fighters. This made it more difficult for enemies to predict the fighter's maneuvers and strategies. These brains were built with basic heuristic processors, enabling a unit to analyze, anticipate, and replicate an opponent's attacks. The Colicoids were the source of the tri-fighter's predatory programming. Alternatively, a tri-fighter could be further modified to serve as a vehicle for a pilot.

The compact and heavily armed tri-fighter was equipped with four laser cannons and discord missiles situated on its underside. Support clamps were connected to its wing cannons, and the nose-tip laser cannon, one of the tri-fighter's weapons, was positioned at the front of the fighter, near its photoreceptors and port sensors. The droid starfighter also carried a payload of proton torpedos, pistoeka sabotage droids, or concussion missiles. Radiation vents and cooling radiators were located on its repulsorlift wings, which were designed for flight within a planet's atmosphere. The droid also included three drive thrusters and a gyroscopic reactor core. To instill fear in organic adversaries, the fighter's three-armed structure was designed to resemble the skull of a fierce and terrifying prehistoric predator from Colla IV.

Tri-fighters, produced by Phlac-Arphocc Automata Industries, served within the Separatist navy during the Clone Wars, a conflict lasting three years between the Separatists and the Galactic Republic. The Confederacy military deployed the tri-fighter during the later stages of the Clone Wars, with its use documented by 20 BBY. During one engagement in the war, the tri-fighter designated DIS-347 inflicted critical damage on a Republic BTL-B Y-wing starfighter/bomber.
During the Battle of Sullust in 20 BBY, droid tri-fighters from Trident group one and group two operated under the command of Dark Acolyte Asajj Ventress within her fleet. During the conflict, Ventress, piloting her Ginivex-class fanblade starfighter, instructed the first team of tri-fighters to target the starboard engines of the Venator-class Star Destroyer Resolute, while the second team was ordered to attack the port deflector shield generators. Ventress then proceeded to make a direct assault on the Resolute's bridge. After a clone navigation officer on the Resolute reported the loss of the port deflectors, Ventress launched an attack on the flagship, crippling the vessel. Ventress, followed by several tri-fighters, then moved to engage Jedi Generals Obi-Wan Kenobi and Anakin Skywalker.

Following Ventress's attack on Kenobi's Delta-7B Aethersprite-class light interceptor, the two Jedi separated, with Ventress pursuing Kenobi's starfighter and the tri-fighters chasing Skywalker's fighter, a situation the Jedi General joked about. As three of the droid starfighters pursued him alongside a Recusant-class Commerce Guild destroyer, Skywalker noticed three additional tri-fighters on the other side of the warship. He used this to his advantage, tricking the initial three fighters into colliding with the others. Skywalker then moved to assist Kenobi, creating an opportunity to blast Ventress's starfighter. Both Ventress and Kenobi then crash-landed in the Separatist command ship's hangar. Unfortunately for those on-board, Count Dooku, the Separatist Head of State, had been instructed by his Sith Master, Darth Sidious, to kill Ventress, so he ordered that TJ-912 fire on the command ship. After its destruction, Dooku ordered the Separatist fleet to retreat. However, Ventress survived the assassination attempt and went to the planet of Dathomir, where she planned her revenge with the Nightsisters.
Tri-fighters later participated in the Battle of Lola Sayu as part of the Lola Sayu defense fleet. Despite their efforts, Republic forces managed to escape the planet. The fighters also saw action during the Battle of Umbara, fighting alongside the Umbaran Militia. Despite the betrayal of Jedi General Pong Krell, the Republic ultimately secured victory.

Following the failure of her scheme to use Savage Opress against her former master, Ventress returned to Dathomir. Dooku discovered this and instructed General Grievous, the Supreme Commander of the Droid Army, to eliminate all of the Nightsisters. After battle droids under Grievous's command landed on the planet, two tri-fighters and two Hyena-class Droid Bombers approached the Nightsister lair and opened fire. The Separatists eventually gained the upper hand, wiping out Mother Talzin's clan, though Ventress, Mother Talzin, Merrin, and Shelish survived.
Before General Kenobi could dispatch Clone Commander Cody to retrieve a group of Jedi younglings on the Crucible, a Separatist fleet under General Grievous's command emerged from lightspeed and attacked the Jedi's fleet. Republic forces began to be overwhelmed, and tri-fighters accompanied Grievous's Sheathipede-class transport shuttle during the engagement. Grievous and a force of battle droids soon boarded Kenobi's flagship, the Negotiator, prompting the Jedi General to activate the Venator-class Star Destroyer's self-destruct.

Later, the Separatists invaded Cato Neimoidia, leading the Republic to launch a defense. General Skywalker and his Padawan, Jedi Commander Ahsoka Tano, led a starfighter squadron and brought a group of Republic gunships. Upon entering the planet's atmosphere, several tri-fighters launched from a Providence-class Dreadnought, and three of the droids moved to attack the Republic starfighters. After eliminating at least two Z-95 Headhunters, one of the tri-fighters launched buzz droid missiles, which caused several of the sabotage droids to attach to Skywalker's Eta-2 Actis-class light interceptor. These droids forced his astromech droid, R2-D2, to crash the ship on a cliff.
During the Battle of Ringo Vinda, droid tri-fighters were present in the Confederate-held section of the Ringo Vinda space station, alongside vulture droids and other combat droids. At the same time, General Skywalker, Clone Captain Rex, and ARC trooper Fives launched a rescue mission to free clone trooper Tup, who was being transported on a Maxillipede shuttle for examination by the Sith. The three successfully rescued the captured trooper.

Later in the war, General Grievous and Count Dooku attempted an arms deal for a massive kyber crystal with Sugi arms dealers on Utapau. Jedi Generals Kenobi and Skywalker eventually arrived on Utapau and attempted to thwart Grievous's plans, but the Separatists managed to transport the crystal aboard a Maxillipede shuttle to bring it to a supply ship. The Jedi pursued the crystal using a freighter, but Grievous, flying his personal starfighter Soulless One, and three tri-fighters gave chase. As they flew through a Separatist fleet, three vulture droids also joined the pursuit. Kenobi took control of the weapons systems and managed to eliminate all three tri-fighters and one of the vultures.
After the Maxillipede boarded the supply ship, Kenobi and Skywalker infiltrated the ship using escape pods, and Skywalker had their freighter crash into the supply craft's hyperdrive to prevent a Separatist escape. The two learned that the crystal could refract and intensify energy. Knowing this, Kenobi had several Armored Assault Tanks fire at the crystal in the ship's hangar. While they and Grievous escaped the doomed ship, the crystal overheated, releasing an energy wave that began to destroy other Separatist ships. As the wave erupted, three tri-fighters were flying near a Recusant-class destroyer, and at least two of the fighters were destroyed.

Tri-fighters also saw action during the Outer Rim Sieges campaign, including a skirmish between a Republic and Separatist fleet led by General Grievous. During this battle, tri-fighters engaged Z-95 Headhunters in dogfights over the Providence-class Dreadnoughts, and the battle on Lokori also saw their deployment. Tri-fighters participated in the Battle of Cato Neimoidia as well, facing off against Jedi General Plo Koon and his wingmen. They were also present at the Battle of Yerbana, where they attacked Z-95 Headhunters and Republic gunships attempting to support Commander Cody and the 212th Attack Battalion, who were under fire from Separatist ground forces. The tri-fighters launched surprise attacks on the Headhunters and gunships, weakening them. Despite this, the Republic won the battle on Yerbana.
Tri-fighters were also part of an attack fleet during the Battle of Coruscant, a major Separatist offensive against the Republic capital world under Grievous's command. One tri-fighter was modified by the pilot Volan Das and used as his personal starfighter. During the surprise attack, Grievous landed in the Executive District, captured the Republic's Supreme Chancellor, Sheev Palpatine, and brought the chancellor to his flagship, the Invisible Hand. Jedi Generals Skywalker and Kenobi infiltrated the Invisible Hand to rescue Palpatine. The elite Clone Flight Squad Seven escorted them, and their V-19 Torrent starfighters created a breach through the tri-fighters attempting to stop them, although the squad lost two pilots. As the Jedi and clone trooper pilots approached Grievous's warship, a tri-fighter destroyed an Aggressive ReConnaissance-170 starfighter. Several tri-fighters then pursued another ARC-170, prompting the clone pilot to request assistance. While Skywalker wanted to help, Kenobi insisted that they continue with their mission.

After a tri-fighter destroyed an ARC-170, another flew near the vulture droid that launched buzz droid missiles at the Jedi. Skywalker and Kenobi defeated the buzz droids and boarded the Invisible Hand. Skywalker killed Count Dooku, Palpatine was rescued, Grievous abandoned the craft, and the starship crashed on Coruscant's surface. Grievous ordered all Separatist ships to retreat, but some vessels, including droid starfighters, remained. Clone trooper pilots spent hours eliminating leftover tri-fighters, vulture droids, and Hyena bombers. The battle marked the Separatist's final stand, as their fleet was destroyed and Dooku was dead. Clone pilot Davijaan "Odd Ball" later provided a postmission summary, noting that Squad Seven's V-19s had punched through the tri-fighters.
Shortly after the Battle of Coruscant, Chancellor Palpatine, secretly the Sith Lord Darth Sidious, transformed the Republic into the First Galactic Empire. Anakin Skywalker, now Darth Vader, had all Separatist droid units, including the droid tri-fighters, deactivated.
During the Imperial Era, some tri-fighters continued to be used by the Free Ryloth Movement and Berch Teller's rebel cell.
By the time of the skirmish aboard a cruiser stolen from the Pyke Syndicate by the mercenary Ledesmar, a collection of droid tri-fighters was present on the ship.
In Star Wars Battlefront II, the droid tri-fighter is classified as an "Interceptor" for the Confederacy of Independent Systems faction.