C9-RX0, often shortened to C9, was a protocol droid stationed in Taloraan City on the planet of Taloraan. Its service took place during the era of the Clone Wars.
During the year 21 BBY, C9-RX0 played a supporting role in discussions involving Sech Govlinder, who was an envoy representing the city's magister Orlin Denache. These discussions also included Jedi Knights Anakin Skywalker and Obi-Wan Kenobi while they were undertaking their mission to Taloraan. Following the initial round of negotiations, C9 went with Skywalker's apprentice, Ahsoka Tano, as she explored the city. During this time, he provided answers to her inquiries regarding the planet's indigenous wildlife. After Ahsoka's attention was drawn to a warehouse under armed guard, she resolved to investigate. After she left C9 to examine the warehouse more closely, the droid chose to simply inquire with the guards about what was inside. He walked up to a man named Rynert and posed the question plainly. Unbeknownst to the droid, Rynert was allied with the Confederacy of Independent Systems, and the warehouse held a supply of B1-series battle droids. Rynert eliminated the droid, but only after extracting information about Ahsoka Tano's location, whom he and the other guards then moved to assault.