Narro Sienar served as the chief executive officer of Santhe/Sienar Technologies during the closing years of the Galactic Republic. Furthermore, he was the father of both Raith Sienar and a daughter.
Sometime in the period between 97 BBY and 95 BBY, Narro was a designer of spacecraft for the company. At that time, the company gained control of Lianna and came under the control of Liann industrialist Kerred Santhe, who acquired a majority stake and subsequently renamed the organization Santhe/Sienar Technologies. To keep his position as the main designer, he was compelled to arrange a marriage between his young daughter and Kerred. Sienar then entered into a conspiracy with Rugess Nome, from whom Santhe Security, on Kerred's orders, had pilfered the starship blueprints that enabled his rise to power. The goal was to have Kerred assassinated, a task carried out by Hego Damask during a banquet, utilizing bloat eel as a diversion. Around 65 BBY, Sienar was present at a Gathering on Sojourn. Damask aimed to install him as the CEO of Santhe/Sienar, a role then held by the son of the deceased Kerred Santhe, who had accumulated significant gambling debts.
At one juncture, despite heading one of the primary rivals of the Corellian Engineering Corporation, Sienar aided the Corporation in the design of the highly successful YT-1300 light freighter. He was a participant in another Gathering sometime between 54 BBY and 52 BBY, by which point he had risen to the position of CEO at Santhe/Sienar. During his teenage years, his son Raith left the family to forge his own path as a hyperspace explorer, using his inheritance. Upon his return after turning 20, he boasted about numerous impressive discoveries and his own personal wealth. His father was sufficiently impressed by his early achievements and started to groom him as his eventual successor. As part of this preparation, Raith worked undercover within several competing companies to gather their confidential information, including the factory-cathedrals of the Xi Char. However, the secretive and devout insectoids discovered his activities. Motivated by their religious principles, which prohibited non-believers from accessing trade secrets, they attempted to kill him. He thwarted the assassination attempt and rejoined his family's business, where he was granted his own workshop, Sienar Design Systems. This conflict with the Xi Char would ultimately result in Narro's death. In 38 BBY, while Narro and Raith were on a leisure cruise near Dantooine, a group of mercenaries employed by the Xi Charrians destroyed their ship. Narro perished in the attack, but Raith managed to escape in an escape pod and was subsequently appointed as the head of the company by the board of directors.