Trolza (RussianZАО "Троллейбусный завод" (Тролза)), formerly known as the Uritsky factory or simply Uritsky, is a former trolleybus manufacturer in Russia, located in EngelsSaratov oblast. In the Soviet era it was known as ZiU (RussianЗавод имени Урицкого, Zavod imeni Uritskogo, plant named after Moisei Uritskiy) or Uritsky factory.

ZiU/Trolza has built over 65,000 trolleybuses. Historically, the most numerous models of ZiU production were the MTB-82, the ZiU-5 and the ZiU-9 (also known as the ZiU-682). The ZiU-9 is the most widely produced trolleybus in history. The factory has exported its production to various countries, including ArgentinaBulgariaColombiaGreeceMongoliaHungarySerbia etc.