As a son of Morgan and Patricia Katarn, farmers from Sulon, he was educated at the Imperial Academy on Carida when his mother was killed by a malfunctioning BT-16 perimeter security droid. He became a decorated member of the Imperial Special Operations, but his father, unknown to him, was a Rebel supporter. During the attack on his homeplanet of Sulon (officially a Rebel attack), he lost his father. Kyle began to hate the Rebel Alliance and supervised many Imperial operations against it. One such operation was the assault on AX-456, a Rebel comm center situated on an asteroid that beamed anti-Imperial propaganda to the citizens of the Barma sector and that linked up to similar facilities in the adjacent Haldeen and Kliap sectors. His success at leading this mission earned him the Imperial Medal of Valor.
Eventually he learned from Jan Ors, an Imperial Intelligence double agent (actually working for the Rebellion) that his father was tortured and killed for treason. He agreed to free Jan and defected, becoming a neutral mercenary. Jan introduced Kyle to Mon Mothma, the leader of the Alliance, and he became an important spy.
In the computer game Star Wars: Dark Forces, Katarn is introduced as a mercenary working for the Rebel Alliance under Mon Mothma. Kyle was secretly dispatched by Mothma on missions deemed too dangerous or sensitive for actual Rebel operatives, and was extremely well paid for his services.
Shortly before the events of Star Wars Episode IV: A New Hope, Katarn single-handedly infiltrated an Imperial facility on the planet Danuta to retrieve the plans for the first Death Star. The plans would eventually be forwarded to Princess Leia Organa, leading to her pursuit and capture by Darth Vader.
After the destruction of the first Death Star, the Empire retaliated against the Rebel Alliance by unleashing the Dark Trooper Project, a secret Imperial research initiative which was manufacturing powerful battle droids to attack Alliance worlds. After several adventures (including run-ins with Jabba the Hutt and Boba Fett), Katarn defeated the Dark Troopers and destroyed the Dark Trooper Project aboard its flagship, the Arc Hammer.
Upon witnessing Katarn's performance in battle, Vader made an off-hand remark about the young mercenary's Force potential.
In the aftermath of his victory over the Dark Troopers, Katarn supervised the training of crack Alliance undercover commandos and quickly formed a tight-knit group of agents known as the Katarn Commandos. Lieutenant Page, one of his cadets, took over as the leader of the squad when Katarn retired. Katarn also took part in a mission put together by Corwin Shelvay, in which he teamed up with Force-sensitives Shira Brie and Erling Tredway to sabotage the second Death Star en route to D'rinba IV.
The game Jedi Knight: Dark Forces II takes place one year after the events of the film, Star Wars Episode VI: Return of the Jedi. It began with Kyle being visited by the spirit of the Jedi Qu Rahn, who told him of the Jedi heritage of his father: Morgan Katarn had helped the Jedi Master close off the Valley of the Jedi: a resting place for deceased Jedi that have become one with the Force and a nexus for Force energy. Kyle traveled to his father's workshop, located on Sulon, a moon of Sullust, to find the family droid named WeeGee to decipher a message from his father. After his father's message was complete, the droid then ejected Rahn's lightsaber from an internal storage compartment, which Kyle took and practiced with momentarily before leaving to track down Rahn's killers. He embarked on a journey where he battled against the Dark Jedi faction, led by the Dark Jedi Jerec, who had murdered his father and Rahn. During his journey, he fought the other six Dark Jedi who followed Jerec. He defeated, but spared, Yun. He then fought and killed Gorc, Pic, and Maw, but, with each duel, Kyle brought himself closer to the dark side. His adventure took him to a secret Jedi burial ground, the Valley of the Jedi, where the spirits of many Jedi and Sith lay quiescent, trapped there after the Battle of Ruusan. This site was a nexus of power from which Force-sensitives could draw great energies of the Force. Jerec was attempting to gain this power for his own ends.
Kyle's ship, the Moldy Crow, was destroyed when Kyle attempted to escape the crash of Jerec's ship. Kyle escaped although the crash left him unconscious. One of the last Dark Jedi, Sariss, and her adopted son Yun, pulled the unconscious Jedi from the wreckage. Boc, another Dark Jedi, destroyed Katarn's lightsaber and left to assist Jerec. Sariss was about to kill Kyle, but Yun, impressed by Kyle sparing his life in the beginning, blocked her blow with his lightsaber. Sariss' blade was deflected and struck Yun, mortally wounding him. As Kyle woke up, he heard Yun saying Katarn shouldn't have died a coward's death and that he deserved a true battle. Yun breathed his last, possibly returning to the light side. With his lightsaber destroyed, Kyle picked up Yun's saber and defeated Sariss, being careful not to fall to the dark side in the process. (That is, if the player chooses the light-side path -- if the player has fallen to the dark side prior to that moment in the story, Yun will not save you and you will fight him instead of Sariss)
Kyle rushed to the Jedi Temple and confronted Boc, who wielded two lightsabers, but was no match for Kyle's dueling skills. After defeating Boc, Kyle rushed in to stop Jerec. The two dueled, and Kyle disarmed Jerec. The Dark Jedi tried and failed to turn Kyle to the dark side (again, if you choose the light path). Katarn tossed Jerec his lightsaber back. Picking up his weapon, Jerec lunged at Kyle, igniting his lightsaber. Kyle shifted aside but left his lightsaber blade in Jerec's path, severing his right shoulder and arm. The wound was fatal, and Jerec died. Kyle freed (according to prophecy) the souls of the Jedi, trapped millennia ago by Lord Kaan.
Although the player has the option to follow the dark side alternate ending, in which Kyle takes on the Powers of the Valley and becomes the new Emperor, the canonical ending is that Kyle continued to be a light side Jedi.
Kyle continued working with Jan for the New Republic, cooperated with Bey, Dash Rendar and Guri on an insertion mission to the Tof fortress world Saijo and nearly razing Space Station Kwenn while apprehending a Ketton spy. Kyle took a more permanent role with the New Republic and served with Page's Commandos, executing missions in various worlds like Kashyyyk, Boudolayz, and Garos IV.
Skywalker made a second offer to Katarn, and this time he accepted, believing that further training would help him tame his dark self. Kyle gave up his former lightsaber and built his own blue saber. Kyle developed a friendship with fellow Jedi trainee Corran Horn, but when two students of the Academy fell to the dark side, Kyle's fear of the dark side multiplied. Kyle gave up studying the Force, gave his lightsaber to Luke Skywalker and returned to his mercenary ways as Jan Ors' partner. New Republic Intelligence reports of his missions suggest Kyle's tactics were particularly "bloodthirsty." He almost always deliberately made a complete search for targets. Of particular note was a mission on Tatooine on which only one Imperial survivor was left alive for interrogation. The Imperial was so shocked all he revealed was that his orders originated from a planet named Kejim.
Three years after the events of Jedi Knight: Mysteries of the Sith, Kyle's adventure continues in Jedi Knight II: Jedi Outcast. Kyle encountered many enemies like the Rodians Beedo, and Reelo Baruk, the Gran Ree-Yees, and the Dark Jedi Desann and his apprentice, Tavion.
Jan Ors was taken prisoner by Desann and apparently killed by Tavion. Angered by his partner's death, Kyle returned to The Valley of the Jedi on Ruusan to restore his powers, but was warned by the Jedi spirit of his late father of the corrupting power of The Valley. He also warned Kyle about the coming dangers. Kyle then stepped in The Valley's core beam to restore his Force Powers and once again trod dangerously close to the dark side. He returned to the Jedi Academy on Yavin 4 to begin training again and to retrieve the lightsaber he had left with Luke Skywalker for safe-keeping, also learning Desann was a fallen student of Skywalker's. Luke and Kyle then set across the galaxy to bring Desann to justice. During his travels, he learned that Jan was still alive. She was eventually rescued, allowing Kyle to overcome his thirst for revenge. He learned as well that Desann had located the Valley of the Jedi by following Kyle and had begun to create an army of Dark Jedi "Reborn" warriors to rule the galaxy. These warriors, called Shadowtroopers, were artificially infused with the Force and were clad in Cortosis armor, an armor that is resistant to lightsabers. Kyle tracked Desann to the Jedi Academy on Yavin 4, and after an intense lightsaber duel, killed him, ending his plan for domination.
After Desann's defeat, Kyle decided to keep his lightsaber and continue in the ways of the Force as a Jedi Master and the Battlemaster at Luke's academy.
In the game Jedi Knight: Jedi Academy, Kyle is relegated to the role of supporting character. He becomes the Master of two students, Jaden Korr and Rosh Penin. Both students being talented, they quickly learn Kyle's wisdom. Kyle's quest in the game is to defeat the Sith cult known as the Disciples of Ragnos. Rosh eventually succumbs to the dark side and joins the cult. Kyle again meets Tavion, leader of the cult, who possessed a device known as the Staff of Ragnos, and plans to resurrect the ancient Sith Lord Marka Ragnos.
Kyle's other student, Jaden Korr, eventually becomes a Jedi, but depending on the player's choice, Jaden may either turn to the Dark Side by killing Rosh, or remain on the Light Side by forgiving him. In the latter choice, Kyle is proud of his student, who defeats Tavion. If Jaden goes to the dark side, Kyle later duels with his former pupil, who overpowers him using the Staff of Ragnos, stolen by defeating Tavion. Jaden escapes, apparently becoming a commander of the Imperial Remnant, and Kyle then questions whether or not he should be a Jedi, taking a leave of absence to apprehend Jaden.
While it is not yet explicitly clear which ending is canon, the official stance from Lucasfilm on games where players can choose between the light side and dark side has traditionally been that the light side ending is the canon one.
Kyle heard a rumor that the Sith still existed. Due to his experiences on Dromund Kaas, Kyle investigated after the invasion, following clues from Ord Sedra in the Clacis Sector to Yaga Minor, resulting in the Cloak of the Sith. During the mission, Kyle was captured by the Dark Jedi Daye Azur-Jamin, who presumably attempted to turn Kyle back to the dark side. After a successful rescue mission led by Jan Ors and Jaden Korr, Kyle revealed all that he knew about the new threat. A Force-sensitive Yuuzhan Vong is causing havoc in the galaxy, and it's apparent that an even more powerful threat looms on the horizon. (So far, these events haven't appeared in any stories, but only in the SWRPG and other supplemental material.)
During the Dark Nest Trilogy, Kyle is one of four Jedi Masters who attempts to destroy the dark nest. Kyle also speaks his mind during a Master's Council session, where he stands up to Chief of State Cal Omas. He, along with Corran Horn and other Masters believed that Jaina Solo and Zekk could be the next leaders of the dark nest. In The Swarm War, Kyle led a squadron of Jedi Stealth X's against the Killiks.
Kyle appears in the Legacy of the Force novels Bloodlines, Sacrifice, and Exile as a Jedi Master participating in Council meetings. In Bloodlines, he helps to point out the "embarrassment" to the Jedi Order of Jacen Solo's actions in apprehending Corellians on Coruscant. Additionally, he plays the part of a devil's advocate in Exile regarding Leia Organa's supposed betrayal of the Galactic Alliance, though he reasserts his loyalty to Leia by being first to formally declare his faith in her at the meeting's end.
In Fury, Kyle Katarn led a Jedi strike team to destroy Jacen Solo. After a fierce duel, Kyle was severely wounded when Jacen stabbed Kyle in the chest with his crimson lightsaber. Two of the Jedi present helped to carry the wounded Katarn to safety while the Jedi Valin Horn - son of Jedi Master Corran Horn - continued the fight in an attempt to hold Jacen off. Katarn survived, but the Jedi Thann Mithric died when he was decapitated by Jacen Solo. Later, he is part of a rescue mission with Jagged Fel to rescue Luke Skywalker, Han Solo, Leia Organa Solo, Ben, Saba Sebatyne, R2-D2, and Iella Wessiri when they capture Allana.
Kyle appears in subsequent sequels and further comics, games and novels. He also has an entry in the Star Wars Roleplaying Game and was a premiere figure of the New Jedi Order faction in the Wizards of the Coast Star Wars Miniatures. The Wizards of the Coast web series The Dark Forces Saga highlighted his background, as well as those of most of the other heroes and villains found in the games.
Likewise, in Mysteries of Sith, Jedi Outcast and Jedi Academy, Kyle is exclusively a polygonal model, without FMV scenes, made to look like a slightly older Court, voiced by Rino Romano in Mysteries of the Sith, and Jeff Bennett in the latter games. For the audio dramatizations, he is portrayed by Randal Berger.