G'vli G'Sil served as a male Human politician during the time of the Second Galactic Civil War. As a senator within the Galactic Alliance Senate, G'Sil was given the role of head of the Galactic Alliance's Security Council. In the year 40 ABY, with tensions escalating between the Alliance and the planet of Corellia, terrorist acts occurred on G'Sil's homeworld, which was the Galactic Alliance capital of Coruscant. Following these attacks, G'Sil collaborated with Chief of State Cal Omas to develop an idea for a division of the Alliance military specifically for domestic security. This proposed division eventually evolved into the Galactic Alliance Guard. Later that same year, Omas was removed from his position by GAG leader Jacen Solo and Galactic Alliance Defense Force Admiral Cha Niathal. Despite Niathal's urging for G'Sil to compete for the office once elections were reinstated, G'Sil declined, fearing he would also be deposed. Surprised and taken aback by the shift in leadership, G'Sil went back to his work on the Security Council, at one point becoming involved in a disagreement between the Alliance member world Murkhana and the Verpine species.
G'Sil, who was born on Coruscant, the capital of the Galactic Alliance, began a career in politics, eventually becoming a senator in the Galactic Alliance Senate. By 40 ABY, he had risen to the role of Chairman of the Alliance's Security Council.
In 40 ABY, Coruscant was targeted by terrorist attacks, which stemmed from increasing tensions between the planet Corellia and the Galactic Alliance. Following these incidents, G'Sil felt that the Alliance had overlooked domestic issues and collaborated with Cal Omas, the Galactic Alliance Chief of State, to create a new concept: a division within the Galactic Alliance Defense Force focused on internal matters like terrorism. Subsequently, G'Sil attended a meeting in the Security Council conference room within the Senate Building alongside Omas, Jedi Masters Luke and Mara Jade Skywalker, and Jedi Knight Jacen Solo. It was during this meeting that G'Sil and Omas, who wished for Mara Jade Skywalker to lead the new division, presented their idea to the Jedi, who initially resisted it. Although the Jedi did not initially endorse the security branch, G'Sil and Omas eventually persuaded Jacen Solo to assume control of the organization, which later became the Galactic Alliance Guard.
The Guard immediately started counter-terrorism operations in Coruscant's Corellian Quarter, rounding up and detaining Corellians suspected of terrorist activity. The Guard's actions sparked widespread outrage among Coruscant's Corellian population, who viewed it as a violation of their rights. G'Sil was present at a Senate session where Corellian Senator Charr informed the Alliance of Corellia's withdrawal of its ambassador from Coruscant. Subsequently, G'Sil met with Omas, Solo, and Cha Niathal, the Galactic Alliance Defense Force Admiral, in Omas' office. Omas and G'Sil expressed their displeasure with Solo and Niathal for the rising tensions on Coruscant resulting from the treatment of Corellian prisoners, but they backed down after a disagreement.
Later in the year, Jacen Solo and Cha Niathal orchestrated a power grab, seizing the Chief of State position from Cal Omas, who was then placed under house arrest. Following the coup, Niathal, now part of a duumvirate, visited G'Sil in his Senate Building office, just as she was about to deliver a speech on the situation. G'Sil was shocked to learn that Omas had been relieved of his duties and that Dur Gejjen, the Corellian leader, had been assassinated by GAG forces. Niathal assured G'Sil that regular elections would resume once hostilities with Corellia ceased, and she asked him to run for the Chief of State's office, as Niathal and Solo believed he aspired to that position. However, G'Sil refused, fearing he would also be overthrown. After Niathal and G'Sil's conversation, Niathal announced the change in leadership to the Senate, with G'Sil adding that, due to the increasing chaos on Coruscant, the Galactic Alliance needed to deploy its own troops to restore order.
Some time after the change in administration, G'Sil met with Solo, Niathal, and Nav Ekhat, the senator representing the Outer Rim planet of Murkhana. Ekhat was concerned about the Verpine, an insectoid species known for manufacturing weapons and starships, who were complaining about what they perceived as unfair competition from Murkhana. The Verpine had formed an alliance with the Mandalorian warrior clans, granting them access to Verpine technology. This meant that if the Mandalorians sided with Corellia in the conflict, their access to Verpine technology could pose a threat to the Alliance. Ultimately, Jacen Solo entrusted Niathal with handling the Mandalorian situation. Later in the war, G'Sil's relationship with Niathal deteriorated, and he even refused to acknowledge the Mon Calamari's presence in the government. In 41 ABY, as the war continued, G'Sil sent a message to Chief of State Solo, requesting a meeting to discuss security matters. Due to the numerous systems seceding from the Galactic Alliance, the remaining Senators tended to form committees. Despite the loss of Senators, G'Sil's Security Council continued to meet quarterly. However, Solo informed G'Sil that he was unavailable that day and would reschedule the meeting for a later date. Despite G'Sil's insistence that they must meet due to a legal requirement, Solo refused, stating that he would simply change the law requiring the meeting.
After the coup, neither Niathal nor Solo would remain in power for long. As the war between Corellia and the Alliance intensified, Solo embraced the dark side of the Force, becoming the Sith Lord Darth Caedus. He significantly increased his power, becoming almost dictatorial, and became the sole Chief of State after Niathal was removed from power at the Second Battle of Fondor in 41 ABY. Caedus' growing power caused a rift between the Alliance and the Jedi; some elements of the Alliance fleet sided with the Jedi, and Caedus was eventually killed by his Jedi twin sister Jaina, severely weakening the Galactic Alliance faction that had supported Solo. The Galactic Alliance, now free from Caedus' influence, forced Corellia's surrender under the new Chief of State Natasi Daala. After the war, the Galactic Alliance Guard, G'Sil's brainchild, was disbanded.
As the leader of the Galactic Alliance Security Council, G'Sil prioritized the well-being of Galactic Alliance citizens, especially those on his homeworld of Coruscant. Following the terrorist attacks on the planet in 40 ABY, G'Sil was a vocal advocate for increased focus on domestic security, which led him to help establish the Galactic Alliance Guard. However, when the Guard's actions led to further unrest among Corellians on Coruscant, G'Sil quickly confronted Jacen Solo and Cha Niathal, the leaders of the Galactic Alliance Guard.
Some politicians and military figures in the Alliance, particularly Solo and Niathal, viewed G'Sil as ambitious and believed he coveted Omas' position as Chief of State. However, after Solo and Niathal ousted Omas as Chief of State, G'Sil refused to run for the position, fearing he would also be overthrown. When Niathal informed G'Sil of Omas' removal from office, G'Sil was surprised and shocked, as he had worked closely with Omas and considered him a friend and ally.
G'Sil's first appearance was in Karen Traviss' novel Legacy of the Force: Bloodlines, the second book in the nine-part Star Wars: Legacy of the Force series. He also appeared in Traviss' novel Legacy of the Force: Sacrifice, which was also part of the Legacy of the Force series. Although these are his only appearances in Star Wars canon, the character was mentioned in Traviss' novel Legacy of the Force: Revelation and was included in The Complete Star Wars Encyclopedia.