The T-54 and T-55 tanks are a series of Soviet main battle tanks were introduced just as the Second World War ended. The first T-54 prototype was completed at Nizhny Tagil by the end of 1945. The T-54 eventually became the main tank for armoured units of the Soviet Army and armies of the Warsaw Pact countries, and many others. T-54s and T-55s have been involved in many of the world's armed conflicts since the later part of the 20th century.
The T-54/55 series eventually became the most-produced tank in military history. Estimated production numbers for the series range from 86,000 to 100,000. They were replaced by the T-62, T-64, T-72, T-80 and T-90 tanks in the Soviet and Russian armies, but remain in use by up to 50 other armies worldwide, some having received sophisticated retrofitting.