Heavy tank
The Char 2C was one of the largest tanks ever produced. At the start of World War II, France and the Soviet Union were the only countries to have inventories of heavy tanks, such as the Char B1, T-35, and KV-1. The Matilda II was designed under the British infantry tank concept which is similar to the heavy tank having thick armor and weighing more than their other tanks. It’s usually separate because they have less firepower with their cruiser tanks (comparable to mediums) at the time having the same main armament but more machine guns. Later war examples were the German Tiger I and II, as well as the Soviet IS series. Note that "heavy" versus "medium" is more a question of tactical roles than weight; the Panther, for example, was a "medium" tank that outweighed most Allied "heavy" tanks.
History of the tank
During the war, German tank design went through at least three generations, plus constant minor variations. The first generation included such prewar vehicles as the Panzerkampfwagen (or Panzer) I and II, which were similar to Soviet and British light tanks. The Germans converted their tank battalions to a majority of Panzer III and Panzer IV medium tanks after the 1940 French campaign. However, the appearance of large numbers of the new generation T-34 and KV-1 Soviet tanks, that were unknown to Germans until 1941, compelled them to join a race for superior armour and gun power. The third generation included many different variants, but the most important designs were the Panther (Panzer V) and Tiger (Panzer VI) tanks. Unfortunately for the Germans, lack of resources combined with emphasis on protection and firepower and a penchant for overly complex design philosophies in nearly every part of an armoured fighting vehicle's design compromised the production numbers. However, an assault gun casemate-hulled development of the Panzer III, the Sturmgeschütz III, would turn out to be Germany's most-produced armoured fighting vehicle of any type during the war, at just over 9,300 examples, a popular design which could also be very effectively tasked to perform the duties of a dedicated anti-tank vehicle.