Name - after the truculent medieval queen - given to two models of British Army "infantry tank" (by contrast with faster but underarmoured "cruiser tanks") of the early years of World War II, more properly known as Infantry Tanks Mk I and Mk II. Both were slow - 20 to 25 kph flat out for the Mk II, a mere 10 kph for the Mk I - and not particularly heavily armed - the Mk I, intended basically as a mobile pillbox, carried only machine guns; the Mk II mounted a 2-pounder (40 mm) gun - but were heavily armoured, and virtually impervious to the 20 mm and 37 mm guns mounted on most German tanks of the era (and the standard issue Pak 37 anti-tank gun), and would have posed serious problems to the Germans had Rommel not hastily developed the doctrine of using his heavy 88 mm Flak guns in an anti-tank role at the battle of Arras (May 1940).
The majority of the obsolete Matilda Is were lost after the Dunkirk evacuation and the fall of France, but the Mk II stayed in production and front-line service for a couple of years, most notably in the Western Desert, before being replaced by the heavier-gunned Valentine and Churchill models; a number were supplied to the Russians in 1941 but being by then vastly inferior to the native T34 saw little use after the initial crisis on the Eastern Front other than for training; the Germans too used a small number of examples captured in France and Russia. Some later models were fitted with 3" howitzers for infantry support, and the Australian army, which continued using the Matilda in jungle fighting up until 1943, also developed a flamethrower version (the "Frog").
A preserved Matilda II can be seen in the Imperial War Museum, London.
Presumably inspired by the tank, the name of one of the house robots in UK Robot Wars, armed with ramming tusks and formerly a chainsaw, later replaced by a vertically mounted flywheel.