Sifo-Dyas, a Jedi Master of the human male persuasion, originated from Minashee. He famously set in motion the creation of the Grand Army of the Republic by the Kaminoans, a venture undertaken more than a decade prior to the Clone Wars. This Jedi, native to the Cassandran Worlds, possessed the rare power of foresight. This ability secured him a position on the esteemed Jedi High Council before the Invasion of Naboo. His visions revealed a future war poised to engulf the galaxy, leading him to believe the Galactic Republic would require an army to secure victory. However, the Jedi Council rejected his warnings, resulting in his removal from their ranks. Undeterred, he secretly pursued his vision, contacting the Kaminoan cloners under the false pretense of authorization from both the Council and the Galactic Senate for the creation of a Republic army. This action inadvertently placed him in the sights of the Sith, who sought to seize control of the cloning project.
Around the time the Invasion of Naboo occurred, Supreme Chancellor Finis Valorum tasked Sifo-Dyas with conducting clandestine negotiations with the Pyke Syndicate. He then departed for Oba Diah accompanied by Silman, Valorum's personal aide. However, Darth Tyranus, the Sith Lord who was once Sifo-Dyas' friend and Jedi Master known as Dooku, betrayed him. Tyranus hired the Pykes to target Sifo-Dyas' T-6 shuttle. The Pykes successfully shot down his ship above the Oba Diah moon. Sifo-Dyas died as a result of the crash, though Silman survived only to be taken prisoner by the Pykes. Consequently, Tyranus and his Sith Master, Darth Sidious, provided funding for Sifo-Dyas's army of clone troopers, enlisted the services of bounty hunter Jango Fett as the genetic template, and instructed the Kaminoan cloners to include Order 66 within the clones' behavioral modification biochips (which Sifo-Dyas had originally intended as a safeguard against treacherous orders). They also manipulated the Jedi Order into leading the army when the Clone Wars erupted. It took years for the Jedi to uncover the Sith's plot and unearthed the truth surrounding Sifo-Dyas's death.
Originating from Minashee in the Cassandran Worlds, Sifo-Dyas came into existence in 102 BBY during the latter part of the High Republic Era. He was the offspring of a fisherman. As an infant, he was discovered by the Jedi Order through Jedi Master Cherff Maota, and was eventually placed into the Hawk-Bat Clan, under the guidance of Tera Sinube, where he forged a close friendship with Dooku of Serenno.

During their time as initiates, they and their youngling clan accompanied numerous other Jedi on a journey to Serenno for a celebration. While engrossed in the festivities, young Sifo-Dyas collided with Grand Master Yoda, prompting the other Masters, including Tera Sinube and Yula Braylon, to rush to the elder Jedi's aid with concern. Despite this Yoda insisted Sifo-Dyas had learned from his mistake, and the boy promised to be more careful in the future.
Later, while the Masters were busy demonstrating various lightsaber stances, Dooku ran off after seeing a young girl he thought he recognized. Sifo-Dyas eventually found his friend and the girl, Dooku's sister Jenza, buried under the rubble of the Great Assembly after it collapsed during a groundquake. While the Masters lifted the rubble off of them he tried to comfort his friend. Upon arriving back on Coruscant, Sifo-Dyas was present when Dooku received a box containing a communicator, that allowed him to correspond with his sister over the following decades.
At some point Sifo-Dyas discovered the journal of Klias Teradine, which revealed the existence of the Bogan Collection in the Jedi Archives, with this secret he convinced Dooku to help him break in. Together, they used sand levitation to get past the magnetic lock, allowing them to view the vault of forbidden artifacts linked to the dark side of the Force. As Sifo explored, observing scrolls, weapons, and other ancient devices, Dooku's eye was drawn to a large piece of metal that he connected with through the Force. As Sifo was distracted his friend drew closer to it, and heard the sound of a beast drawing near. This frightened the boy, who summoned a Force wave that destroyed many of the items in the chamber and threw Sifo-Dyas through a glass cabinet.
The noise quickly drew the attention of Chief Librarian Restelly Quist, who caught the apprentices and brought them to the infirmary. While there, Sifo's arm was put in a bacta cast to help heal his broken bone, and he was confronted by Masters Yoda and Braylon, who each expressed disappointment in the way they had violated their trust. It was here that the pair of younglings first met Jedi Master Lene Kostana, who came to express her concern that the Bogan Collection had not been sealed effectively since children were able to break in.
Sifo and Dooku watched the masters discuss their conflicting philosophies concerning the appropriate way to prepare young Jedi to confront the dark side, and when their discussion was concluded Yoda assigned Sifo-Dyas and Dooku to decipher the Lothal Papyri as punishment. Under the watchful eye of Master Quist they worked through their penance. After a couple days studying crop rotations Master Kostana stopped by and spoke to them, playfully referring to the Grand Master as a "goblin," and wishing the initiates good luck. After she left, Sifo discovered that she had slipped him a book, The Bestiary of Darth Caldoth. His friend urged him to turn it in, but young Sifo-Dyas refused.
Upon completing the Initiate Trials, Sifo-Dyas participated in the Padawan Tournament where younglings would compete against each other in combat in order to attract prospective masters. Sifo-Dyas came up against Dooku, who defeated him blindfolded and with one arm behind his back. However, his friend elected not to demand his surrender, and allowed his fellow initiate to duel him to a stalemate so he might better impress the masters. Immediately following this, Sifo-Dyas was taken as a Padawan learner by Master Kostana, much to Dooku's initial disappointment as he had hoped to be chosen as her apprentice.
During his time as a Padawan, he visited Palek with Kostana and there managed to acquire a crystal that seemed to be similar to a kyber crystal. Upon returning to the Jedi Temple, Sifo-Dyas gifted this crystal to Dooku. While on Palek, a hyperstorm took place.
Under Master Kostana, his mind was opened to the current of the Cosmic Force, which granted him very vivid Force vision of the future. One of these visions involved a planet being engulfed in flames. This turned out to be a warning about the coming Protobranch solar storm before the event had even occurred circa 85 BBY. His teacher encouraged him to take these visions seriously, but Master Kostana also did what she could to hide her apprentice's talents from the Jedi Council, fearful that they might interpret his talent for foresight as being dangerous.
Over the years, Sifo-Dyas and his Master dedicated their efforts to locating dark side artifacts, and the Bogan Collection expanded greatly during their time together. That so many Sith relics were surfacing, further convinced them that evil was on the rise again.
Around 82 BBY, the Jedi Council learned Dooku was communicating with his sister in violation of the Jedi Code. He agreed to halt further contact on the condition that he be allowed to attend his mother's funeral. Since Master Kostana and Sifo were already planning on searching the Gordian Reach, which was near Serenno, she convinced the council to allow her to take the apprentice to Mantero, the funeral moon. While there a protest broke out that ended with the Countess's casket knocked over. The Jedi knew the prideful Count Gora would not allow the embarrassing incident to be reported by the HoloNet, and agreed not to inform the council of what had happened.
With that done they went immediately to Asusto, following a lead they had discovered earlier while on a mission to infiltrate a smuggler ring on Karazak. While there they encountered a group of Abyssin who were transporting nerve disruptors. Still emotionally unstable from his mother's funeral, Dooku killed all of the smugglers in a fit of rage, but the moss-coated ground trapped them so they were unable to escape. This was an ambush, laid by the Presagers of Hakotei who intended to kill them in order to generate visions of the future. The moss held them as they were tortured, they bore witness to dark images of war, and the return of the Sith. As their foresight overwhelmed them, Dooku lashed out with Force lightning, killing their captors and freeing Sifo-Dyas and Master Kostana.
Knowing the council would not approve of her exposing apprentices to the dark side, Master Kostana once again insisted they not be informed about what had transpired on Asusto. To help Dooku refocus himself in the light, Sifo and his master taught him an ancient ritual using bindings that allowed him to restore balance within himself.
Sifo-Dyas learned much under Master Kostana, though he never got along with her convor.

Following their mission to Asusto, Sifo-Dyas achieved the rank of Jedi Knight. However, due to the intensity of his visions, Master Kostana continued their collaboration. They both felt their partnership was effective, drawing inspiration from the ancient Jedi practice of working in pairs. Despite this, certain Jedi, such as Dooku, were quick to point out she was no longer responsible for his well being, but his former Master was happy to keep their partnership alive. Sifo saw little of his old friend after becoming a Knight, and the emotional toll his visions took on him caused him to develop a stutter. Sifo and Kostana remained active over the years, frequently embarking on missions and rarely returning to the Jedi Temple.
In 42 BBY, Sifo and his Master returned to Coruscant and were approached by a disgraced Master Yula Braylon. The former Councilor had been asked to transport Dooku and his family protocol droid, D-4, back to Serenno, which had been invaded by Abyssin pirates. The mission was not sanctioned by the Jedi Council and Braylon did not wish to put herself in a worse position with them, but she knew Master Kostana would be happy to help.
Together, Sifo-Dyas and Master Kostana took their old friend back to his homeworld. Their ship was shot down, and Sifo was separated from his old Master and Dooku during the fight. Things escalated even further when the Jedi was granted another vision of the future, one where a large gathering of people were chanting Dooku's name. This unnerved Sifo-Dyas and left him unable to participate in the remaining fight. It was soon discovered that the Abyssin had been hired by Dooku's brother, Count Ramil. Dooku confronted his brother, hoping to deescalate the situation, but when the planet's ruler threatened to kill everyone present, the Master summoned a Sith warbeast to cause mayhem and create an opening so that he might strike the Count down. Ultimately, Dooku lost control of the Tirra'Taka, and was forced to kill it.
With the Serenno Civil War now over, Sifo-Dyas witnessed his old friend lay claim to his family's title of Count of Serenno. With his sister Jenza's support the people began to chant his name, just as Sifo-Dyas had predicted. They also were present when Dooku informed Yoda that he was resigning from the order, becoming the twentieth member of the Lost before saying goodbye, promising that they would see each other again.
Later in his life, Sifo-Dyas ascended to the rank of Jedi Master. By 39 BBY, he had also become a prominent member of the Jedi High Council, the governing body of the Order, during the final decades of the Galactic Republic. However, prior to the Invasion of Naboo, tensions began to surface between Sifo-Dyas and his fellow councilors. In one instance, Sifo-Dyas was barred from recruitment duties when the Council learned that he often ignored procedures in an effort to swell the ranks of the Jedi Order, which led to him to selecting inviable candidates and creating situations that complicated other's livelihoods. In one notable instance, he sought candidates from a orphanage on Kwenn but did not take time to understand their situations, which led to the abandoning of young Zilastra while her friends were taken to the Jedi Order, causing her to develop anti-Jedi sentiment that cumulated towards her assassinating Jedi later in her life.
Later, he would foresee an upcoming full-scale conflict and as a result, started advocating for the creation of an army for the Republic. The rest of the High Council deemed his ideas too extreme, and Sifo-Dyas was removed from his position. Even though the other Jedi had rejected his project, he found a way to carry it out without their consent.
In 33 BBY, Sifo-Dyas contacted the Kaminoans, known for their clone hatcheries, to secretly commission the creation of a clone army for the Republic. Dyas personally commissioned Prime Minister Lama Su to create the clone force and pretended it was a request of the Galactic Senate. Although it was not known how the Sith caught wind of the project, Dooku, who had left the Jedi Order and become a disciple of the Sith Lord Darth Sidious, later claimed Dyas had willingly worked with him to create the clone army because of the future Dyas had foreseen.
One year later in 32 BBY, Master Sifo-Dyas was approached by Finis Valorum, the Supreme Chancellor of the Republic, on a secret mission to the planet Oba Diah, the headquarters of the Pyke Syndicate. Valorum, who was aware of the Jedi Master's expertise with the criminal underworld, asked Sifo-Dyas to negotiate a settlement with the Pykes, whose control of the galaxy's raw spice production was threatening a "full-scale war" in the underworld of Coruscant. Sifo-Dyas was accompanied by Silman, the Chancellor's personal aide. The mission was kept secret from the Jedi Council, as the Senate committee dealing with the matter feared the political repercussions of openly negotiating with the Pykes.
However, Sifo-Dyas was never able to complete the Chancellor's mission; shortly after he arrived on Oba-Diah, the High Council called him to deal with another conflict: on Felucia, a skirmish had broken out between the local tribes, and Sifo-Dyas was assigned to quell the conflict. As a consequence, both Sifo-Dyas and Silman were diverted to Felucia aboard T-6 shuttle 775519.

However, neither man would ever reach their destination, for Sidious needed Sifo-Dyas' clone army for his plot to bring down the Jedi and the Republic. Unwilling to leave Dyas alive as a loose end, Dooku, who had since apprenticed himself to Sidious under the title of Darth Tyranus, betrayed his former friend by paying the Pyke Syndicate to destroy Sifo-Dyas' shuttle. Since the syndicate wished to gain an advantage over rival crime families, and Tyranus' substantial offer would allow them to do just that, they accepted and shot down Sifo-Dyas' shuttle over the Oba Diah moon. After inspecting the wreckage, they turned over the Jedi Master's corpse to Tyranus as proof that the deed was done. While Sifo-Dyas had died in the crash, Silman was still alive when the Pykes inspected the wreckage. They decided to keep the Chancellor's aide locked up in their prison as insurance against future action by Tyranus, recognizing that anyone who would pay to have a Jedi assassinated was exceedingly dangerous. The spice dealers also left the Jedi's lightsaber at the crash site.
Tyranus subsequently took Sifo-Dyas' body and traveled to Felucia. Posing as another Jedi, Tyranus deceived the Felucian tribal elders into believing that Sifo-Dyas had died in the conflict, and had his body cremated according to Felucian custom—thus leaving the Jedi Council unaware of where and how the Jedi Master had truly died.
Following Sifo-Dyas' death, Tyranus and Sidious took over his Clone Army project. Sifo-Dyas had originally planned for a behavioral modification biochip to be instilled in each Clone, which was to be a safeguard against rogue Jedi. However, Sidious and Tyranus retooled the chips to brainwash the Clones into murdering the Jedi. Posing as a Jedi, Tyranus presented the chip to Lama Su and Nala Se, and deceived them into believing Sifo-Dyas's intention. Dooku also travelled to the Jedi Temple on Coruscant to erase any mention of Kamino in the Temple Archives by way of making use of Sifo-Dyas' codes.
Ten years after the Jedi Master's death, the army he had commissioned was discovered by Obi-Wan Kenobi, a Jedi Knight who was investigating on Kamino following the murder of the bounty hunter Zam Wesell by a mysterious colleague of hers, Jango Fett. To his great surprise, Kenobi was greeted by Taun We, a Kaminoan, as if they had been expecting his visit. Prime Minister Su then informed the Jedi of the existence and progress of the clone army ordered by Sifo-Dyas some ten years ago. Although Kenobi had no knowledge of the army, he feigned that his trip to Kamino was in fact an official visit by the Order to inspect the army, so he played along. He bluffed his way into the heart of the hatcheries, and was introduced to the original source of the clones, which was none other than Jango Fett. As soon as he took his leave of the Kaminoans, Kenobi contacted the High Council and told them of the clone army and how Sifo-Dyas was supposed to have commissioned it. The Council members, however, had no more knowledge of the army than Kenobi did, though they did inform Kenobi that whoever had ordered the army had not received the sanction of the Council. Ultimately, Sifo-Dyas' clone army ended up being used at the behest of the Republic, and the conflict between the Separatists and the Republic was named "the Clone Wars" after it.

In 19 BBY, the last year of the Clone Wars, a Jedi mission led by Plo Koon and Commander Wolffe found a lightsaber belonging to the long-dead Sifo-Dyas on Oba Diah's moon. This unexpected discovery prompted Yoda, Obi-Wan Kenobi, and Anakin Skywalker to investigate his decade-old demise. Meanwhile, Tyranus' master, the mysterious Darth Sidious, was furious to discover that the Jedi were investigating the loose end that was Sifo-Dyas. He ordered Tyranus to clean up his affairs before it was too late. Shortly afterward, during their duel on Oba Diah, Dooku claimed to Anakin Skywalker and Obi-Wan Kenobi that Dyas had helped him.
As part of the Sith illusions created by Darth Sidious and Darth Tyranus' ritual, Sifo-Dyas appeared to Yoda on Moraband. His phantom was being tortured, bound by electricity. The specter begged Yoda to release him, offering in exchange the identity of the Sith Lord. However, Yoda saw through him with his Sith eyes and refused the offer, causing him to merge into Sidious.
At the end of the war, Chancellor Palpatine, who finally revealed himself as Darth Sidious, used the biochips and his secret protocol to force Sifo-Dyas's Clone army to turn against the Jedi Order, thereby initiating the Great Jedi Purge, which saw the death of several Jedi Masters. In an ironic twist of fate, unknowingly manipulated and deceived by the Sith Lords, Sifo-Dyas contributed to the destruction of the Jedi in his effort to save the Order.

One of the few Jedi who managed to evade the initial purge was a Padawan learner known as Ferren Barr. While in hiding, Barr made an inquiry into the reasons for the Jedi Order's swift and utter downfall. After he came to the realization of Dyas's unknowing part, Barr created a file concerning the Jedi Master. This file was included in a collection of files stored on an R1-series astromech droid called Endee, which pertained to important figures involved in the plot.
In the year 3 ABY, while residing on Dagobah, Yoda recalled how one of his pupils, Krrsish, had a premonition of a friend's descent to the Dark Side. After Yoda learned that Dooku was aware of this vision, Dooku reminded Yoda of the Jedi Council's treatment of Sifo-Dyas, expressing his hope that Krrsish would find a more compassionate path than the one Dyas had taken.
The murder of Sifo-Dyas at the hands of the Pyke Syndicate was documented within the "Index of Organizations," a survival guide distributed by Carson Teva during the period of the New Republic Era.
Sifo-Dyas, a male human, shared a close friendship with his fellow Jedi, Dooku, though their bond did not prevent Dooku's betrayal of Sifo-Dyas in the time leading up to the Clone Wars. Dooku asserted, however, that Sifo-Dyas had willingly assisted him in the creation of the clone army.
In an early version of Star Wars: Episode II Attack of the Clones, the Jedi who made contact with the Kaminoans was named "Sido-Dyas," which was a fabricated identity for Darth Sidious. Obi-Wan Kenobi stated that he had never heard of him, and Mace Windu verified that no Jedi by that name had ever existed. In the draft, one instance of Sido-Dyas was accidentally written as "Sifo-Dyas," and this became the name that was ultimately chosen.
George Lucas had initially promised that his backstory would be revealed in Star Wars: Episode III Revenge of the Sith. However, after Lucas shifted the film's focus to center on Anakin, he was compelled to remove several plot elements related to Attack of the Clones, including Sifo-Dyas's backstory. It wasn't until "The Lost One," an episode from the sixth season of Star Wars: The Clone Wars, that the character's canonical background was established. Paul Nakauchi provided the voice for his hallucination appearance in the episode "Sacrifice."