A descendant of the legendary Jedi Grand Master Luke Skywalker, Kol Skywalker was raised as a Jedi and trained to wield the Force. Along with his brother Nat, he served as Jedi Knight. When the Jedi Council of Seers saw Skywalker's importance to a mission with Imperial Intelligence agent Morrigan Corde, he was assigned to it. Serving with her, he fell in love. They had a relationship for as long as two years, marrying secretly, before Skywalker impregnated Corde, who gave birth to a son named Cade. Corde, unprepared to be a mother and summoned back into service, departed despite Skywalker's pleas to stay with him and their son. Skywalker was left to raise Cade alone. Corde went on to become the Director of Imperial Intelligence and a member of the Moff Council under the name Nyna Calixte, apparently without Skywalker's knowledge of her double identity.
Skywalker disliked politics and formality; instead, he spent most of his time as a trainer on Ossus, where he provided tactical training to the Jedi students from his own considerable expertise. Skywalker had a particular student of his own, Wolf Sazen. Skywalker trained the Zabrak Padawan to Knighthood; Sazen eventually achieved Mastery himself and took Skywalker's son Cade as his own apprentice. Skywalker eventually took the Twi'lek Shado Vao, a friend of Cade's, as his Padawan learner, training Vao to a mastery of the lightsaber. With Sazen now his peer, the two became close friends as well as master and student.
Despite his dislike of politics, Skywalker became a leading member of the Jedi Council. In that position, he conceived of and championed the Ossus Project, in which Yuuzhan Vong shapers used their biological techniques to terraform a barren patch of Ossus. Skywalker wished to help integrate the Yuuzhan Vong, long stigmatized due to the war they had brought to the galaxy, into society and rehabilitate their reputation by proving that they could use their knowledge to heal the worlds they had devastated in the past. He worked closely with Master Shaper Nei Rin to bring it to fruition, developing a friendship with her. With that project successful, the Galactic Alliance was persuaded to allow the shapers to restore life to worlds devastated by the Yuuzhan Vong War. The project went awry, with individuals becoming malformed and plant life dying.
Skywalker and the Jedi worked with Rin to discover the cause and suspected sabotage, correctly, but blame fell on the Yuuzhan Vong and in 127 ABY the Galactic Empire invoked the Treaty of Anaxes and declared war. Skywalker and the Jedi were able to convince the Galactic Alliance to back them and protect the Yuuzhan Vong in the war. The Sith order, until then hidden—and secretly responsible for the sabotage of the Ossus Project—emerged on the Empire's side and helped turn the tide of the war against the Jedi and Galactic Alliance. After three years of battle, Skywalker was called to speak his mind to the Galactic Alliance Triumvirate about the possibility of a strike at Caamas to capture Galactic Emperor Roan Fel. He spoke against it, having sensed it was a trap, but Rear Admiral Piers Petan and Triumvir Nu Toreena, a detractor of the Jedi who also blamed them for the war, pushed the plan forward anyway, resulting in the defeat of the Alliance Defense Fleet. With that, the Galactic Alliance surrendered. Roan Fel called upon the Jedi to surrender as well, but Skywalker withdrew the Jedi to Ossus with Fel's guarantee of safe passage.
The forces of Darth Krayt, Dark Lord of the Sith, followed the Jedi withdrawal from Coruscant to Ossus. Led by Darth Nihl and supported by by Imperial troops commanded by Rulf Yage, the Sith assaulted the academy on Ossus. Woken by the impending battle, Skywalker organized a defense while evacuating the young students. He and Sazen made a stand at the landing platform on which the evacuation shuttle stood, holding off waves of stormtroopers while Vao and Cade Skywalker, among the older apprentices present, shepherded the younger Jedi students into the shuttle. Skywalker and Sazen could sense the Sith oncoming and ordered Cade and Vao to take off when all the others were aboard, prepared to give their lives to save the younglings. Cade refused to follow instructions, however, joining the battle with his father. Skywalker ordered his son to follow his master's instructions and leave with the children.
As Cade departed for the shuttle, Nihl approached at the head of a column of Sith warriors. Skywalker and Sazen engaged them, but Sazen quickly received grievous injuries. Skywalker drove Nihl back and stood over his former student's body, summoning Sazen's lightsaber and warning the Sith back. He stood alone against an army of Sith but successfully held them back despite being surrounded; however, upon seeing Sazen fall, Cade once more left the shuttle and went to his father's aid. Skywalker admonished his son for placing his emotions above his duties, and commanded him to take Sazen, not yet dead, from the field and evacuate. Tearfully, Cade complied. Skywalker continued battling, holding back the Sith and standing upon a heap of the dead. Nihl, however, was able to strike Skywalker with Force lightning, killing him as Cade watched from inside the shuttle. Skywalker sent a final message through the Force to Vao, ordering him to launch the shuttle.
The transport escaped, though Cade launched in a fighter to defend it and was disabled. He was picked up by pirates, who did not know that he was a Skywalker, and brought back to the surface to help them loot the academy, where Cade found his father's body lying as it had fallen on the landing platform. Upon returning from a mission into the Ossus wilderness to find samples, Rin found Skywalker's body lying exposed and gave it a proper funeral. During the cremation, Skywalker's body disincorporated, becoming one with the Force. To honor Skywalker and the Jedi legacy, they gathered all the Jedi artifacts remaining which they could and kept them safe in the bowels of the academy.
Cade became a bounty hunter and turned to death sticks, rejecting the Force. Luke Skywalker's Force ghost appeared to him at times, urging him to take up his family legacy, but Cade wished only to be left alone, free from the burden of saving the galaxy. Cade continued to hear his father's words in his mind as well, but was never able to sense his presence, driving even farther into bitterness and depression. Skywalker was unable to counsel his son as his anger blocked him from communicating. Cade eventually returned to Ossus in 137 ABY and began training under Sazen, Vao, and K'Kruhk before departing for Coruscant to rescue Hosk Trey'lis, a Jedi he had turned over to the Sith as a bounty hunter. Rin gave him Kol's lightsaber, which she had recovered and repaired with a lambent crystal after the original crystal had suffered battle damage. Cade took to it Coruscant, where he was captured by Darth Krayt and the lightsaber was taken from him and encased by Krayt to honor a foe even he respected. Cade, meanwhile, joined the Sith while Calixte, again using her Corde identity, devised a plan to free him. When Cade confronted Krayt, Kol appeared to him as a Force ghost to suggest he use his healing powers in reverse to break the transparisteel and free his lightsaber. Cade did so, taking up his father's lightsaber and attacking the Sith before escaping.
Kol and Luke Skywalkers' Force ghosts later appeared to Cade, warning him of a coming threat.