The T-54 was the original version of the T-55 series. The production of the T-54 was superseded by the T-55, but it remained in service next to the T-55.
T-54: Original T-54 produced in limited numbers in three minor variants. Features different shaped turrets and no stabilization for main armament.
T-54A: T-54 with horizontal stabilization for D-10TG cannon, new sights and radio and automotive improvements. T-54AK is the command version with additional radios.
T-54B: T-54A with stabilization in both planes for D-10TS cannon, new sights and infrared searchlight next to barrel. T-54BK is the command version with additional radios.
T-54M: T-54 with various improvements to bring it up to T-55 standards, including the more powerful V-55 engine.

The T-55 was the follow on to the T-54. The T-55 featured many improvements and was produced in much larger numbers than the T-55.
T-55: The original T-55 is a much improved version of the T-54. The T-55 features a more powerful V-55 engine, an NBC system, a turret floor and carries more fuel and ammunition. Was fitted without DShK on the turret roof until retrofitted in 1972. T-55K is the command version with additional radios.
T-55A: T-55 with much improved NBC shielding, removed the bow machine gun and has the PKT as a coaxial machine gun instead of the SGMT. Was fitted without DShK on the turret roof until retrofitted in 1972. T-55AK is the command version with additional radios.

The T-55M and T-55AM are improved versions of the T-55 and T-55A. The upgrade includes improvements in firepower, mobility and protection. The firepower is improved by the ability to launch the Bastion anti-tank missile from the barrel, the Volna fire control system, improved stabilization, a laser range finder and new sights. The mobility is improved by fitting a V-55U engine, improved suspension and new tracks. The protection is improved by adding BDD bra (or brow) armor to the turret, rubber side skirts, smoke grenade launchers and appliqué armor. The T-55M-1 and T-55AM-1 are fitted with the V-56-5M engine.

The T-55MV and T-55AMV are improved versions of the T-55 and T-55A. The MV package features the same improvements as the T-55M but instead of the bra armor ERA tiles are fitted. The Kontakt-1 ERA is mounted on the turret front, sides and roof, the glacis plate and hull sides. The T-55MV-1 and T-55AMV-1 are fitted with the V-56-5M engine.

The T-55AD is a T-55A fitted with the Drozd active protection system and several other improvements that was developed for the USSR naval infantry. A total of 250 have been converted. It is also incorrectly known as teh T-55AMD as it features several improvements found on the T-55AM, such as a new radio, new sights and improved stabilization. The T-55AD-1 also has the more powerful V-46-5M engine. The Drozd system relies on 4 missile on each side of the turret to intercept incoming missiles. By todays standards the Drozd system is found rudimentary due to its limited capability of interception.

The Ti-67 is a collective designation for T-54 and T-55 in Israeli service. Israel captured many T-55 from Arab states during various conflicts. Israel put many to use in its own army. Some with only minor alterations such as new camouflage and markings. Others were extensively upgraded, with a new 105mm cannon for instance.
Tiran-1: Virtually unmodified T-54 in Israeli Army service.
Tiran-2: Virtually unmodified T-55 in Israeli Army service.
Tiran-4: T-54 with additional stowage and M1919 machine gun on turret roof. The Tiran-4Sh also features a new 105mm L7 cannon.
Tiran-5: T-55 with new communitions gear, additional stowage, coaxial and roof mounted M1919 machine gun on a ring mount and many featured a 12.7mm M2HB machine gun over the barrel. The Tiran-5Sh also features a new 105mm L7 cannon.
Ti-67s: Tiran-5Sh with Detroit Diesel engine, new transmission, improved gun stabilization system
Blazer ERA, Matador fire control system, improved suspension, fire suppresion system and night vision systems. Also known as Tiran-5 Model S or Ti-67 Model S.

The M-55 is a Slovenian upgrade of the T-55 that is based on many Israeli components.
M-55 S: T-55 fitted with a 105mm L7 cannon, new fire control systems, improved sights and Super Blazer ERA on the turret, glacis plate and upper sides. All M-55 S were subsequently upgraded to S1 standard.
M-55 S1: The M-55 S1 is a futher improved M-55 S that features an 850 hp MAN diesel engine replacing the standard 600 hp engine.

The BTS is an artillery tractor based on the T-54 chassis that can also be used as an armored recovery vehicle. The name BTS stands for Bronetankoviy Tyagach Sredniy, which is Russian for medium armored tractor. The BTS models are also known as the T-54-T and T-55T and are based mostly based on the T-54A chassis, but also on other models such as T-55 and even the occasional T-62. The BTS was supplemented and replaced in Soviet service with the VT-55.
BTS-1: A T-54A without turret that is fitted with a stowage basket.
BTS-2: A BTS-1 fitted with a 3 t crane, produced since 1955.
BTS-4: A BTS-2 fitted with snorkel. The BTS-4B is a BTS-2 with a dozer blade.

The VT-55 is an armored recovery vehicle based on the T-55 chassis that was designed in Czechoslovakia. Unlike the earlier Soviet BTS models all were produced from new chassis. The VT-55 features a 1.5 t crane and loading platform.
VT-55A: VT-55 produced for Warsaw Pact use. Called ZS-55A when fitted with the BTU-55 dozer blade.
VT-55K: VT-55 produced for export customers.

The WZT-1 and 2 are armored recovery vehicles of Polish origin. Later model WZT models are based on the PT-91 Twardy chassis.
WZT-1: Polish armored recovery vehicle based on the T-54 chassis.
WZT-2: Polish armored recovery vehicle based on the T-55 chassis. Fitted with a dozer blade and crane on the left side.

The IMR is an armored engineer vehicle based on the T-55 chassis and is produced since the early 1970's. The name IMR stands for Inzhenernaya Maschina Razgrazhdeniia, which is Russian for engineer vehicle for the removal of obstacles.
IMR: The IMR is fitted with a large dozer blade and a crane that can be fitted with either a bucket or a pincer type grabber.
IWT: The IWT is the Polish equivalent of the IMR and features the same capabilities. The IWT can also be fitted with the PW-LWD mine clearing rockets.

The MTU is a bridgelayer of Soviet origin. Bridgelayer based on T-54 chassis produced since 1958. It carries a single rigid 12.3 meter 50 t bridge to span a 11 meter gap. The name MTU stands for Mostoykladchik tankoviy ustroystvo. The MTU is also known as the MTU-1 and MTU-12. It can be distinguished from the other bridge laying vehicles based on the T-55 series by its single rigid bridge.

The MTU-20 is an improved bridgelayer based on T-55 chassis. It carries a single 20 meter 60 t bridge with folding ends that can span a 18 meter gap.

The MT-55 is a bridgelayer that is based on the T-55 chassis. The MT-55 launches a two part scissor bridge in front of the vehicle. It is more capable than the Soviet MTU series. The MT-55 can be identified by the T-55 chassis in combination with the forward launching scissor bridge.
MT-55: Soviet designation for MT-55A.
MT-55A: Czechoslovak production MT-55 for Warsaw Pact nations. Carries and launches a 18 meter 50 t scissor bridge to span a 16 meter gap.
MT-55K: Czechoslovak production MT-55 for export.
MT-55L: MT-55A with the ability to use the longer 20 m bridge as used with the MT-72.
BLG-60: East German version of the MT-55 with various minor details.
BLG-60M: Improved BLG-60 with the ability to launch 52 meter three part bridges.
BLG-67: Improved BLG-60 of East German origin.
BLG-67M: Improved BLG-60M with similar ability to launch longer bridges.