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.
Valiant tank
The Valiant, under General Staff specification A38, began as a candidate for an assault tank, with the thickest armour on the lowest possible weight, for use in the Far East. It was to be similar in intention to the 40-ton A33 Excelsior although far lighter. As the Valiant managed the same 114 mm frontal armour with only 27 tons, it managed to achieve its primary goal, but only by making unacceptable compromises elsewhere. At a time when British tank design was already at its nadir, this "terrible price for the weight concession" led to what is probably the worst British tank of the war.