The Fiat-Ansaldo M15/42, also known as the M15/42, was an Italian medium tank. Also known as the M.42, it was an improvement on the M13/40 design developed and produced by the same company. By July 1942, the M13/40 and M14/41's problems and defects were well known, so development began on an updated tank with a more advanced engine and modernized gun. The updated vehicle was equipped with a more powerful gasoline engine (diesel fuel was in short supply, and most of it was being diverted to naval needs and army freight transport), with a power output of 190 hp, as well as a modernized 47/32 gun (also used in the M14/41). This new tank served as the basis for the 75/34 M42 and the Semovente da 75/18 self-propelled artillery pieces. A total of 152 vehicles were produced and used by the Wehrmacht, the Royal Italian Army, and the Army of the Republic of Salò following the September 1943 split.

The M15/42 was introduced in Update 1.85 "Supersonic". This combat vehicle has good mobility and a decent gun with a fast reload time. However, its weak armor and mediocre gun traverse speed prevent it from reaching its full potential.