An armoured train is a railway train protected with heavy metal plating and which often includes railway wagons armed with artillery, machine guns and autocannons. Some also had slits used to fire small arms from the inside of the train, especially in earlier armoured trains. For the most part they were used during the late 19th and early 20th centuries, when they offered an innovative way to quickly move large amounts of firepower into a new location. Most countries discontinued their use – road vehicles became much more powerful and offered more flexibility, train tracks proved too vulnerable to sabotage and attacks from the air, and air transportation was an even more flexible to relocate firepower to a new location. However, there were occasional uses in the late 20th centuryand early 21st century Russian Federation used improvised armoured trains in the Second Chechen War of 1999–2009 and the Russian invasion of Ukraine in 2022.

Armoured trains were usually fighting systems, equipped with heavy weapons such as artillery. An exception was the US "White Train", the Department of Energy Nuclear Weapons Transport Train, armoured and escorted by personnel armed with personal weapons.