The FV4034 Challenger 2 (MoD designation "CR2") is a third generation British main battle tank (MBT) in service with the armies of the United Kingdom, Oman, and Ukraine.

It was designed by Vickers Defence Systems (now Rheinmetall BAE Systems Land (RBSL)) as a private venture in 1986, and was an extensive redesign of the company's earlier Challenger 1 tank. The Ministry of Defence ordered a prototype in December 1988. The Challenger 2 has four crew members consisting of a commander, gunner, loader, and driver. The main armament is a L30A1 120-millimetre (4.7 in) rifled tank gun, an improved derivative of the L11 gun used on the Chieftain and Challenger 1. Fifty rounds of ammunition are carried for the main armament, alongside 4,200 rounds of 7.62 mm ammunition for the tank's secondary weapons: a L94A1 EX-34 chain gun mounted coaxially, and a L37A2 (GPMG) machine gun. The turret and hull are protected with second generation Chobham armour, also known as Dorchester. Powered by a Perkins CV12-6A V12 diesel engine, the tank has a range of 550 kilometres (340 mi) and maximum road speed of 59 kilometres per hour (37 mph).

The Challenger 2 eventually completely replaced the Challenger 1 in British service. In June 1991, the UK ordered 140 vehicles, followed by a further 268 in 1994; these were delivered between 1994 and 2002. The tank entered operational service with the British Army in 1998 and has since been used in Bosnia and Herzegovina, Kosovo and Iraq. To date, at least three Challenger 2 tanks are confirmed to have been destroyed in operations; the first was by accidental friendly fire from another Challenger 2 in Basra in 2003, and the two others were during the Russo-Ukrainian War, where the tanks were destroyed under Ukrainian control during the 2023 Ukrainian counteroffensive and Ukrainian incursion into Kursk. Further Russian claims with supporting drone footage show FPV drone strikes on at least two other vehicles. The extent of damage to them is unknown as of the time of writing.

Challenger 2 tanks were also ordered by Oman in the 1990s with delivery of 38 vehicles being completed in 2001. A number of British Challenger 2 tanks were delivered to Ukraine in 2023.

Since the Challenger 2 entered service in 1998, various upgrades have sought to improve its protection, mobility and lethality. This has culminated in an upgraded design, known as Challenger 3, which is set to gradually replace Challenger 2 from 2027.

The Challenger 2 is the third vehicle of this name, the first being the A30 Challenger, a World War II design using the Cromwell tank chassis with a 17-pounder gun. The second was the Persian Gulf War era Challenger 1, which was the British army's main battle tank (MBT) from the early 1980s to the early 2000s.^{[citation needed]}

While the British Chieftain was heavily armed and armoured, its engine and suspension were considerably subpar compared to its contemporaries, leading to poor cross-country performance and a lack of maneuverability.^{[citation needed]}

Some work on further development of the Chieftain had been ongoing since 1968 at the Military Vehicles and Engineering Establishment (MVEE), and several experimental vehicles produced, including one with the recently developed Chobham armour. In September 1978, it was announced that these concepts would be brought together in a new design, MBT-80. Deliveries of the MBT-80 were not expected until the mid-1980s at a minimum. Advances in Soviet armour, especially the apparent upcoming introduction of the T-80, suggested that the UK's tanks would be at a significant disadvantage before the MBT-80 would arrive. After considerable debate, MBT-80 was controversially cancelled, due to high projected costs, significant development delay, and the British military industry being reliant on Iran, which cancelled all orders due to the Iranian Revolution. Instead, in 1978, the British Army ordered the Challenger 1, based on the Shir 2. The final Challenger 1 was delivered to the British Army in 1990.