Lio Partagaz was a human male who held the rank of major in the Imperial Security Bureau. Situated in the ISB Central Office on the Imperial capital planet of Coruscant, he oversaw the ISB board. His primary focus was identifying potential disturbances before they threatened Imperial security. Partagaz was known for rigorously questioning his subordinates about their reports. In one particular ISB board meeting, Blevin, a subordinate, reported on an ambush on Ferrix. Soon after, Partagaz intervened in a dispute between Blevin and lieutenant Dedra Meero, who sought access to the raw data from the Ferrix incident, as she suspected a coordinated rebel movement based on stolen Imperial equipment.
A short time later, an Aldhani rebel infiltration team stole an Imperial payroll from the Aldhani garrison. Following this event, the Empire implemented the Public Order Resentencing Directive, placing the ISB in charge. Meero, still fixated on the Ferrix incident, successfully persuaded Partagaz to transfer the sector to her jurisdiction. Subsequently, the ISB began coordinating efforts to locate the "Axis" of the rebels, who, unbeknownst to the Bureau, was actually Luthen Rael.
In 5 BBY, the human male Lio Partagaz, a major within the Galactic Empire's Imperial Security Bureau, acted as chairman for a gathering of eighteen ISB Investigations personnel. This group, known as the ISB board, convened in the ISB Central Office on the Imperial capital planet of Coruscant to discuss their submitted reports. Partagaz engaged in a discussion with ISB Supervisor Grandi regarding the allocation of budget funds for the Ryloth sector requested by Grandi. Grandi stated the funds would be used for surveillance of anti-Imperial activities, prompting Partagaz to demand specific details by the end of the day. He then inquired with Lagret about the developing conflict on Arvala-6. Lagret explained that he hadn't finished his memorandum of solutions for storage issues related to those displaced by the conflict because his staff was awaiting an assessment from Arvala's ministerial director.
Shortly thereafter, the major posed a question to the attendees regarding the purpose of the Imperial Security Bureau, receiving an answer from Lieutenant Dedra Meero that he considered inadequate. After defining the Bureau as the entity responsible for treating the "sickness" of disorder within the Empire, the major requested further details on the ambush on Ferrix that Lieutenant Supervisor Blevin had provided information on. Partagaz then asked Lonni Jung to elaborate on requests for enhanced protection for traffic heading to the Abrion sector. Jung clarified that these requests were a proactive measure due to an increase in construction shipments destined for the planet Scarif. Following a dispute between lieutenant supervisor Blevin and Dedra Meero over information related to the Ferrix incident, Partagaz intervened, advising Meero to submit her sectors' quarterly report and expressing his satisfaction with her detention figures from Sev Tok.
Soon after, Partagaz summoned all supervisors and their assistants within the ISB for an urgent announcement. They were instructed not to go home, to notify their staff and families, and to submit their Star Sector and Planetary Emergency Retaliation plans by midnight. Days following this announcement, the major attended a meeting led by ISB Colonel Wullf Yularen, who revealed the measures Emperor Sheev Palpatine had decided upon following a robbery on the planet Aldhani conducted by rebels. Palpatine's directives stipulated that every ISB supervisor present at the meeting would have access to resources from the Imperial Army and Imperial Navy.
Shortly thereafter, Partagaz presided over another ISB meeting, where he addressed another report from Jung, which contained three theories attempting to explain the unrest in the sectors surrounding Jung's. Upon the supervisor's request, Partagaz instructed Jung to prepare a survey of all hyperspace lanes leading to Ord Mantell, to be placed on the major's desk the following day. Noticing that Supervisor Blevin appeared "eager," the major inquired if he had good news. However, the news was not positive; instead, the supervisor was accusing Meero of expanding her influence beyond her designated sectors. The ISB major allowed Meero to defend herself, and she revealed that she had compiled material suggesting that the theft of Imperial military equipment across the galaxy was part of a coordinated project carried out by multiple rebel groups. Accepting this explanation, Partagaz assigned the Morlana sector to Meero, considering it a distraction for Blevin. After the meeting, at the major's request, Dedra walked with him briefly, and he advised her to be cautious.
Partagaz later attended another of Yularen's meetings, where he endorsed Dedra's request for resources to capture and locate Andor, as he found the lack of information about Andor's employer, "Axis," concerning. On Ferrix, Meero interrogated Bix Caleen, a local, and communicated her findings—which did not identify "Axis"—to Partagaz. The major speculated that Andor's mother, Maarva Andor, might be communicating with her son, but Meero clarified that this was unlikely, as her forces were monitoring Maarva. Shortly after, the ISB captured a rebel pilot belonging to the Neo-Separatist Coalition and believed Anto Kreegyr was unaware of the pilot's disappearance. Supervisor Dedro suggested that they could allow the pilot and their ship to drift carefully into traffic, a plan which Partagaz approved. The major then requested a meeting with military intelligence regarding Spellhaus. Shortly afterward, Partagaz observed as the pilot lured other rebels into a trap. Jung advised him to show interest in the pilot's appearance in space, as Kreegyr might be watching and would suspect foul play if the ISB did not become interested in the rebel ship and its pilot, a point Partagaz acknowledged. Partagaz later instructed Meero to locate Axis during a meeting with Jung, Lagret, and other ISB members.
Partagaz possessed gray hair and a light complexion. He was known for his level-headedness, a trait that proved valuable in mediating disputes between supervisors, and his extensive experience was highly valued by his subordinates. While strict in upholding the ISB's standards, he was open to new ideas if they were well-supported and would commend or even encourage productive behavior, even if it deviated from tradition.
The major wore a white Imperial officer's uniform adorned with silver-colored epaulets on his shoulders, a pair of code cylinders, and a rank insignia plaque displaying five blue squares.
Partagaz, played by Anton Lesser, was initially featured in the first teaser trailer for the Andor television series, which was released during Star Wars Celebration Anaheim 2022 on May 26 of that year. The major made his debut appearance on September 28 of 2022 in Andor's fourth episode, directed by Susanna White.