Dace Diath, a Human male, distinguished himself as a Jedi Knight under the tutelage of the esteemed Master Vodo-Siosk Baas. His formative years unfolded on Tatooine, where his father, the Jedi Master Sidrona Diath, imparted his initial training. Following this foundational instruction, he journeyed to Ossus to become Master Vodo's apprentice. He became one of the Jedi dispatched to reinforce Ulic Qel-Droma during the Freedon Nadd Uprising on Onderon. Subsequently, he participated in the Convocation at Mount Meru on Deneba and engaged in combat against the Krath throughout the Great Sith War.
A proficient and gifted pilot, he acquired the skill to pilot a Beast Rider's war beasts while stationed on Onderon. Dace Diath, alongside fellow Jedi Qrrrl Toq and Shoaneb Culu, met his death when Aleema Keto employed Sith powers to destroy a star within the Cron Cluster. He was a predecessor to Jedi Master Nico Diath and Padawan Tae Diath.

Sometime before 4017 BBY, Dace Diath entered the world as the son of the renowned Jedi Master Sidrona Diath. He was born and raised on the desert planet of Tatooine. The isolated nature of Tatooine allowed Sidrona to commence his son's training in the ways of the Jedi, guiding Dace toward a profound understanding of the Force. His father's instruction, combined with the secluded environment, enabled Dace to connect with the Force and allow it to flow through him freely. Despite his ability to embrace the Force and his dedication to being an excellent student, Dace felt his progress was slow. This led him to contemplate abandoning his Jedi training, not due to a dislike for the strict lifestyle, but primarily out of fear of disappointing his father. He reasoned that if he didn't try, he couldn't fail.
Recognizing these moments of self-doubt in his son, his father did everything possible to bolster Dace's self-assurance and his belief in the Jedi path. During one such instance, Sidrona observed that the most capable and gifted teachers were often those Jedi who had diligently studied the Force; they possessed a greater understanding of their students' challenges and could guide them toward resolution. Sidrona consistently reminded his son of this, convincing Dace that he was not alone in his struggles and that he might one day become a Jedi Master.
Sidrona Diath routinely instructed Dace in the Jundland Wastes, focusing on both the physical and mental aspects of the Force. Following a particularly frustrating training session in the Wastes, Dace lost confidence in his abilities. As before, Dace sought support from his father, but this time Sidrona offered no comfort. Instead, he told Dace that he needed to learn to rely on the Force completely and to look inward for his destiny, rather than depending on external support. Dace, surprised and upset by his father's words, wandered away from home into the fading light of dusk, attempting to focus his thoughts on the Force and his problem.
He wandered aimlessly through the landscape, the minutes stretching into hours, battling the confusion and inner turmoil that had consumed his mind. He drifted until he was half-frozen, finding himself on the edge of the Dune Sea. Through the swirling mists of confusion, he began to recall memories. The most prominent memory was when his father had taken him as a young child to Ossus to visit the Great Jedi Library. There, he had examined a Jedi holocron, and the gatekeeper had spoken to the young Dace Diath. Dace remembered the gatekeeper saying that a Jedi who perseveres will never fail, and that a Jedi who gives up fails both himself and the Force.
Reflecting on the gatekeeper's words, Diath realized that his own way of thinking was the cause of his difficulties. He concluded that if he could practice, train, and learn under his father without negative feelings about his progress, he would no longer be hindered and would succeed. On his way back home, he understood that his father had withheld help because he would not have accepted these revelations if someone else had presented them; he needed to discover his own path and believe in it without question. Otherwise, he would never fully accept his destiny and overcome his self-doubt.
Dace eventually returned to his father and continued training under Sidrona for another two years. At the end of that time, Dace felt ready to leave his father and travel to Ossus to continue his training at the Jedi training center. Upon arriving on Ossus, he became a student of Jedi Master Vodo-Siosk Baas.

Dace Diath approached his training on Ossus in much the same way he had studied under his father. He diligently studied at the Great Jedi Library, pushed himself to learn new levels of the Force, and continued to improve how he allowed the Force to flow through him. Throughout the new training regimens on Ossus under Master Vodo, Diath adhered to the lessons he learned in the Dune Sea on Tatooine, mastering his self-doubt and excelling in his Jedi training. He impressed Master Vodo so much that when Vodo departed Ossus for Dantooine, he invited Diath to accompany him and continue training under his guidance. On Dantooine, Diath continued his Jedi training under Master Vodo, and was later joined by fellow apprentices Exar Kun, and the Cathars Sylvar and Crado.
After his training, Diath joined Nomi Sunrider, Shoaneb Culu, Qrrrl Toq, and Kith Kark in answering Ulic Qel-Droma's call for reinforcements against the Naddists during the Freedon Nadd Uprising.

Following the capture of Jedi Master Arca Jeth on Onderon, Ulic Qel-Droma requested additional Jedi support from Ossus for the Freedon Nadd Uprising. In response, the entire Jedi assembly on Ossus volunteered, but only five Jedi Knights were selected, including Dace Diath.
The Republic also responded to Ulic's request, sending a fleet of warships to lay siege to the walled city of Iziz on Onderon. Upon arrival, the Jedi cruisers from Ossus circled the area outside Iziz in search of Qel-Droma and his remaining Jedi. Sensing Qel-Droma in a fortress near Iziz, the five Jedi reinforcements rushed to his aid. Diath and the others used Force battle-techniques perfected over centuries, charging into the numerous enemy ranks. During the attack, Nomi Sunrider noted that an energy field was blocking her Jedi Battle meditation, and Diath also noticed something strange. Diath found himself fighting an ancient Sith War Droid radiating dark side energy. Eventually, Diath and the other Jedi reinforcements joined Qel-Droma and the remaining Jedi of Cay Qel-Droma, Tott Doneeta, and Oss Wilum, discovering that King Ommin of Onderon was creating the dark side energies. With the help of Diath and the other Jedi, Ulic Qel-Droma defeated Ommin and broke the dark side's influence over Onderon. After Ommin's defeat, the Jedi entombed Freedon Nadd's remains on Onderon's beast moon, Dxun.
Shortly after the Naddist Revolt, Master Arca Jeth returned to Onderon to inform Diath and the other Jedi about the re-emergence of the Sith in the Empress Teta system. Master Jeth told them about the political coup by the Krath cult, led by the Tetans Satal Keto and his cousin Aleema Keto. The Jedi were surprised that these two young Tetans, who had been on Onderon during the Naddist Revolt, were now deeply involved in Sith teachings. Diath, Qrrrl Toq, Oss Wilum, and Shoaneb Culu were ordered by Master Jeth to go to Ossus and warn the Jedi and Republic leaders about the dangers they had experienced on Onderon and the growing darkness in the Empress Teta System.

With this information, the Republic and the Jedi Order decided to send a combined fleet to aid the remaining Tetan worlds resisting the Krath coup. Diath and several other Jedi joined the task force, arriving in the Empress Teta System just in time to support the last resistance on Koros Major. However, using ancient Sith magic, the Krath forces, led by Satal and Aleema Keto, used suicide tactics to destroy the Jedi and Republic fleet. Diath was one of the few Jedi who survived the attack.
Following the Krath victory at Koros Major, Nomi Sunrider, Tott Doneeta, and Cay Qel-Droma attempted to secretly contact Ulic, who had infiltrated the Krath cult. However, Ulic had begun his descent to the dark side. When Nomi and the others found him, Ulic used dark side energy to push them away, threatening to kill them. The Jedi realized something was wrong and retreated to Ossus. Back on Ossus, Diath and Cay Qel-Droma were asked to test the new, experimental Star Saber Starfighters. During the test flights, Dace narrowly escaped death after losing control of his starfighter in the rocky canyons of Ossus. Although the starfighter exploded on impact, Dace ejected and used the Force to gently lower himself to the ground.
Sunrider and the other Jedi returned empty-handed, and the Jedi decided to launch an all-out assault against the Krath to rescue Ulic. Despite his recent trouble with the starfighter, Diath chose another Star Saber for the attack. However, the rescue failed, with Ulic shunning Sunrider and Cay and choosing to stay with Aleema and the Krath.

Ulic Qel-Droma led a Krath attack fleet to Republic space and launched an invasion of Coruscant, sparking the Great Sith War. Diath, along with many other Jedi, fought on Coruscant, helping defend the city planet from the invading Krath forces. Ulic led the ground attack, but the Krath were pushed back by the combined Republic and Jedi forces. As the Krath retreated, Ulic faced a group of Jedi, including Diath, led by Nomi Sunrider and Vodo-Siosk Baas. Sunrider and Master Vodo used the 'Blocking' technique taught by Jedi Master Odan-Urr to temporarily cut Ulic off from the Force. Diath and the other Jedi added their powers to Sunrider's and Master Vodo's to help imprison Ulic.
After Ulic's disastrous invasion of Coruscant, Exar Kun and Mandalore the Indomitable rescued him from Republic captivity. He returned to lead the Krath forces. Ulic, knowing Aleema had betrayed him on Coruscant, ordered her to lead an attack on the Republic jump station at Kemplex Nine, setting off a supernova. Ulic knew this attack would consume her. Diath, responding to distress signals from Kemplex Nine, organized a Jedi force to investigate.

The Great Sith War had taken a toll on the Jedi, and many gathered on Ossus in 3996 BBY due to the assassinations of Jedi Masters by agents of Exar Kun. Tott Doneeta announced to the assembly that Kemplex Nine was under attack by an ancient Sith ship. Master Thon explained his belief that the Krath attack on Kemplex Nine was a feint, arguing that everything Ulic and Kun wanted was on Ossus. Upon hearing this, Diath, Shoaneb Culu, and Qrrrl Toq volunteered to chase the mysterious Sith ship, while the remaining Jedi protected Ossus.
Arriving at Kemplex Nine, Diath, Shoaneb, and Qrrrl found the area devoid of life, except for the Sith ship commanded by Aleema and Crado. Diath led the attack, noticing the ship powering up its systems. Unbeknownst to Diath and the other Jedi, Aleema had used the ancient weapons on the Sith ship to rip the core from one of the ten stars in the Cron Cluster. The resulting supernova engulfed Dace and the other pursuing Jedi, killing them instantly.
Dace Diath, a Human male with black hair, brown eyes, and brown skin, was known for his hard work and studiousness as a Jedi. As a young apprentice to his father Sidrona Diath, Dace could connect with the Force easily but struggled with his training pace. He often experienced self-doubt and focused on the negative aspects of situations. However, through his father's guidance and self-discovery, Diath overcame his self-doubt and embraced his Jedi destiny.
After completing his training, Diath became a skilled lightsaber warrior, demonstrating his abilities in campaigns against the Sith. He was one of five Jedi chosen to aid Ulic Qel-Droma during the Naddist Revolt. Diath also fought bravely with his lightsaber during the Krath invasion of Coruscant. He was among the Jedi who combined their powers to create a wall of light to contain Ulic-Qel Droma.
Diath was also an experienced and talented pilot, flying dangerous missions for the Republic and Jedi, often being one of the few to return alive. He tested the experimental Star Saber Starfighters and showed his Jedi levitation skills by safely landing after a crash. Dace later led an aerial attack on Kemplex Nine. He also learned to fly the war beasts of Onderon.
Dace Diath first appeared in Star Wars: Tales of the Jedi – The Freedon Nadd Uprising. The Power of the Jedi Sourcebook incorrectly states that Dace Diath and Oss Wilum tested the Star Saber Starfighters. The Dark Lords of the Sith sub-series of the Tales of the Jedi comics states it was Dace and Cay Qel-Droma.
Diath is absent from both the Tales of the Jedi and Dark Lords of the Sith audio dramas, despite his significant role in the events.