Garen Muln was a Jedi Master of the Human species (a male individual) who dedicated his life to the service of both the Jedi Order and the Galactic Republic. During the tumultuous period known as the Clone Wars, he held the military rank of General within the Grand Army of the Republic.
Endowed with Force-sensitive abilities, Garen Muln, a Human, was brought to the Jedi Temple on Coruscant during his formative years. There, he joined a clan consisting of fellow Initiates and began his training in the ways of the Force. As a restless youth, Muln developed a close friendship with Obi-Wan Kenobi, despite their frequent disagreements over minor matters. In 44 BBY, when a dark sider infiltrated the Jedi Temple, Initiate Muln played a crucial role in thwarting the intruder's plans. He cleverly disguised himself as Padawan Kenobi to mislead the intruder. While Muln and Master Ali-Alann impersonated Kenobi and Master Qui-Gon Jinn, they successfully apprehended the Dark Jedi, preventing the Temple's destruction.
Around 42 BBY, Jedi Master Clee Rhara chose Muln as her Padawan, and the two embarked on a journey of training and exploration throughout the galaxy. After successfully completing his Trials of Knighthood, Jedi Muln further specialized as an ace within the Jedi Starfighter Corps. He assisted his former master in establishing a starfighter base on Centax 2 during the Separatist Crisis that plagued the Galactic Senate.
Over the subsequent years, Jedi Muln undertook numerous missions, often partnering with his childhood friend, Jedi Siri Tachi. Together, they embarked on a rescue operation to save Padawan Anakin Skywalker from the clutches of the deranged scientist Jenna Zan Arbor at her laboratory on Vanqor. Shortly thereafter, Muln accompanied Master of the Order Mace Windu and his longtime friend Bant Eerin to the planet Romin, where they once again rescued Jedi Kenobi, Tachi, and Padawans Skywalker and Ferus Olin from Zan Arbor and the dangerous Granta Omega.
As the Clone Wars engulfed the galaxy, pitting the Republic against the Confederacy of Independent Systems, Jedi Muln assumed the rank of General in the Grand Army of the Republic, wielding his lightsaber in the fight against the Separatist Droid Army. By the final year of the war, he had earned the title of Jedi Master and was assigned to lead a small detachment of clone troopers against the Confederate occupation of Acherin. While stationed there, Master Muln engaged in negotiations with Confederate commanders Toma and Raina Quill in an attempt to broker a truce.
However, as the negotiations neared a successful conclusion, Supreme Chancellor Palpatine of the Republic betrayed the Jedi Order, issuing Contingency Order 66 to the Grand Army, falsely labeling the Jedi as traitors. Miraculously, Muln managed to evade the wrath of his clone troopers and escape the planet with the assistance of Commanders Toma and Quill, his former adversaries.
After fleeing Acherin, a wounded and exhausted Master Muln piloted his vessel to Ilum, a Jedi fortress world, seeking refuge from the icy wastelands within the Temple there. Inside this frozen sanctuary, Master Muln encountered another Jedi, Temple instructor Fy-Tor-Ana. Master Ana recounted the destruction of the Temple on Coruscant and the demise of the Order before departing Ilum to search for survivors of the Great Jedi Purge.
Remaining in the Temple's caves for almost a year, Muln was weakened by malnutrition when former Padawan Ferus Olin arrived in search of him. Olin informed Master Muln that his old friend, Obi-Wan Kenobi, was also alive and in exile. Olin then persuaded Muln to leave the planet and embark on a new mission. Reuniting with Master Kenobi in orbit, Muln was too weak to converse with his friend during the journey to Olin's secret asteroid. Olin intended to transform the asteroid's barren surface into a temporary haven for fugitive Jedi, beginning with Muln. Once safely inside the asteroid, Master Muln received medical attention from an old acquaintance, Commander Quill, who was also accompanied by Toma.
As Master Muln gradually recovered, he found renewed purpose in training the young Lune Oddo Divinian, a Force-sensitive boy whose training had been initiated by Master Ry-Gaul. Muln took over the training, instilling in Divinian the principles of the Jedi Path while remaining on the asteroid.
However, the sanctuary that the group of exiles had found on the asteroid was soon shattered when Dark Lord of the Sith Darth Vader, a servant of the Galactic Empire, located the base and launched an attack. Vader was led there by information leaked by General Toma and a spy, Eve Yarrow, whom the group had trusted. The Jedi were left stranded with only an escape pod. Master Muln, along with Masters Ana and Ry-Gaul, placed Lune Divinian in the pod and managed to launch him off-world before the attack could claim his life. Accepting that the future of the Jedi lay in the hands of younglings like Divinian, the three Masters resigned themselves to their fate as Jedi when Vader unleashed his superweapon upon the asteroid, resulting in their deaths.