Virtually all early tanks possessed thick armor to allow them to survive in no man's land. The origins of the class date to World War I and the first tank designs, which were intended to operate in close concert with infantry. However, low reliability and limited resources meant that just 1,347 were produced, compared to roughly 8,800 Pz.Kpfw. The German Tiger I, for example, had similar speed and better terrain-handling characteristics when compared to its main competitor, the significantly lighter Panzer IV medium tank. As mentioned previously, heavy tanks are often extremely expensive and resource-intensive to produce and operate. Although it is often assumed that heavy tanks suffered inferior mobility to medium tanks, this was not always the case, as many of the more sophisticated heavy tank designs featured advanced suspension and transmissions to counteract this drawback. In case of an entirely new design development, which was the case with the German Tiger I, designs often became needlessly complex and costly, resulting in low production numbers. As a result, they tend to be either underpowered and comparatively slow, or have engine and drive train reliability issues. For example, the M103 heavy tank shared many components with lighter Patton tanks, including transmission and engine. Many heavy tanks shared components from lighter tanks. Heavy tanks feature very heavy armor and weapons relative to lighter tanks. Heavy tanks often saw limited combat in their intended roles, instead becoming mobile pillboxes or defensive positions, such as the German Tiger designs, or the Russian KV designs. Heavy tanks achieved their greatest, albeit limited, success when fighting lighter tanks and destroying fortifications. These tanks generally sacrificed mobility and maneuverability for better armour protection and equal or greater firepower than tanks of lighter classes. Heavy tank is a term used to define a class of tanks produced from World War I through the end of the Cold War.

List of modern tanks