During the Galactic Republic, Senate Security Officers, or SSOs, were Republic soldiers who were assigned the duty of protecting the Senate Building on the planet Coruscant along with police officers of the Coruscant Security Force who held the title of Senate Guards.
The SSOs were in service as early as the Great Galactic War and subsequent Cold War. Though they were assigned to the Senate Building and the Senate District, SSOs could be reassigned and deployed like other Republic Military units to military campaigns. In one instance, several SSOs were sent with a Republic fleet to claim the planet of Sebaddon. After the conclusion of the mission, Supreme Commander Stantorrs reassigned some of the SSOs as part of a special unit under the command of Republic Special Forces Lieutenant Larin Moxla.
They were eventually replaced by the more formalized, and separate, Senate Guard organization.
Senate Security Officers first appeared in The Old Republic: Fatal Alliance.