The M4 Sherman tank was produced in several variants, a result of mass production spread across several manufacturers and several years. It was also the basis for a number of related vehicles and Shermans have been modified by several nations, ranging from upgrades to complete hull conversions for another task. Originally designed in 1941, M4 variants were still used by Israel during the 1967 and 1973 wars with its Arab neighbors. The many special duties that a tank might be made to do were just being explored by armies around the world in the early 1940s. Theories of what vehicles were supposed to be engaging enemy tanks changed as vehicles like the Sherman often found themselves up against enemy armor, and consequently some of the most important initial changes centered around up-gunning the basic vehicle. Improving the vehicle's mobility, protection, and creating specific variants for infantry-support roles soon followed. Similar modification of the main armament would be done by the British, who received a number of Shermans through Lend-Lease during the course of the war, producing the Sherman Firefly tank (armed with a powerful 17-pounder tank gun). Many early variants of the Sherman were converted to armored personnel carriers (called "Kangaroos") or armoured recovery vehicles. In preparation for the invasion of Europe by Allied forces in 1944, an amphibious "swimming" version of the Sherman was used. Extensive work on creating mine-clearance devices to be attached to Shermans in some fashion was also conducted up until the end of the Second World War, such as the Sherman Crab mine-flail tank. After the Second World War, large numbers of surplus Shermans were supplied to other nations, most primarily to Africa, South America and the Middle East. Israel became the largest post-war user of Sherman tanks, conducting extensive modifications to keep them in frontline service right up into the early 1970s as tanks, mobile artillery pieces, armored ambulances and many more versions. Many saw action in the 1967 Six-Day War and 1973 October War. Similar modifications and purchases of Israeli-modified Shermans were done in South America where they served on as the last fighting Shermans right up until 1989. There are many variants of the Sherman, ranging from the M4, M4A1, M4A2, M4A3 and M4A4, which also encompass many sub-variants (such as the M4 (105) or M4A3E8 "Easy Eight", among others).

US variants

Over the course of production a number of improvements in the design were introduced. The turret of T20/T23 prototypes with its 76mm gun was adapted to the Sherman and entered production in February 1944; M4 variants with this armament had the suffix "76mm" added to their designations. The use of the 105mm howitzer for equipping close support tanks occurred from 1943. In reaction to fires following penetrating hits, applique armor was added to the outside of the hull. This was followed by internal modification with "wet stowage" jacketing the ammunition racks. Suspension was changed by the use of the stronger HVSS from mid-1944. HVSS had twice the number of wheels per bogie and individual wheels could be replaced without removing the bogie from the hull. Tracks were wider and vehicles had track covers that extended beyond the hull. Other hull modifications included a 47 degree angled glacis for simpler production, larger access hatches and a hatch for the loader and commander's cupola.

US M4 sub-types

US Sherman-based vehicles

Variants without the M4 designation but built on the M4 medium chassis (While some began on the M3 chassis, some subvariants were switched to the M4 chassis during production. These are the models listed here): based on M4 chassis with turret and gun replaced by fixed turret. Equipped with 60,000 lb winch and an 18 feet long pivoting A-frame jib installed. An 81mm mortar was also added into the hull, primarily for screening purposes. Experimental 90mm Gun Motor Carriage T53/T53E1 – 90mm gun mounted on M4A4 chassis. Design modified for dual anti-tank and anti-aircraft use as T53E1 with outriggers for stability. Order for 500 cancelled in 1944 after design rejected by both Tank Destroyer and AA branch of US Army.

US Special Attachment variants

Rocket-firing, flame-thrower, mine-clearing, amphibious, engineer; mostly experimental (indicated by T instead of M).

Lend-Lease service

The M4 Sherman series were widely distributed to allied armies under the Lend-Lease program. Variants served in all theaters, and were the basis of a number of conversions for various uses, including armored personnel carriers and specialized engineering vehicles.

Post-war variants

The M4 Sherman pattern enjoyed a lengthy post-war service all over the world. They were used well into the 1960s and 1970s by some nations, mainly in Africa and Latin America. In some cases, the vehicles were converted for use in a variety of other roles from mobile artillery to ambulances. Conversions were also made for use in civilian industry. There were two common civilian industrial conversions in Canada. The Finning Corporation introduced a shortened chassis with a powerful hydraulic rock drill, which was able to navigate very rough terrain for road construction. The Madill Corporation found a ready market for a range of logging equipment using converted Sherman chassis. Perhaps the most spectacular were spar yarders with an extensible mast with various winches and cables to haul heavy logs up steep slopes.