Panzer VIII Maus
Panzerkampfwagen VIII Maus ("Mouse") was a German World War II super-heavy tank completed in late 1944. It is the heaviest fully enclosed armoured fighting vehicle ever built. Five were ordered, but only two hulls and one turret were completed before the testing grounds were captured by advancing Soviet military forces.
Heavy tank
Heavy tanks achieved their greatest successes both fighting other, lighter tanks, and destroying fortifications with their very large guns. Although it is often assumed that heavy tanks suffered inferior mobility to mediums, this was not always the case, as many of the more sophisticated heavy tank designs featured advanced suspension and transmission precisely to counteract this drawback. But the greatest drawback is cost which translates into production quantities and/or design. The German Tiger I, for example, had similar speed and better terrain-handling characteristics when compared to the significantly lighter Panzer IV medium tank, albeit at the cost of low reliability and only 1,355 were produced compared to 8,800 Panzer IV and over 59,000 Soviet T-34 and over 45,000 American M4 Sherman medium tanks. This case repeated itself in the operational use of the Tiger II of which only 492 were produced.