ZiU-9, or ZIU-9 is a Soviet trolleybus vehicle. Other names and indexes for the same vehicle include ZiU-682 and HTI-682. The ZiU acronym stands for Zavod imeni Uritskogo, which is a plant named after Moisei Uritsky, the Russian revolutionary. Before 1996 this acronym was also a trademark of the vehicle manufacturer. It has been changed to Trolza. The ZiU-9 was put in mass production in 1971 and it was still assembled along with other more advanced trolleybus vehicles in the Trolza factory until 2014. The total number of produced ZiU-9s exceeds 42,000 vehicles. In addition, many copies of ZiU-9 were made in other factories of the former Soviet bloc. This model is the most numerous trolleybus vehicle in the world.