40M Turán I was a Hungarian tank of World War II - a total of 424 were made in two variants: Turan I with a 40 mm gun and Turan II with a 75 mm gun. It was based on the design of the Czechoslovak Škoda T-21 medium tank prototype.

In December 1937 the Škoda workshops prepared a prototype of a medium tank based on the earlier successful LT vz. 35 project. Two prototypes were started and designated S-IIc, but their construction was never finished. The tank weighed 16.5 tonnes (16.2 long tons; 18.2 short tons), was armed with a 47 mm Škoda A9 vz. 38 gun, two 7.92 mm machine guns and its maximum armour was extended to 30 mm. Finally, the S-II-c was to have a better 13.8 liters engine giving 250 hp; this increased the maximum speed to roughly 50 km/h.

After Germany annexed Czechoslovakia, the prototypes were finished under the new designation of T-21, which in turn was a predecessor of a new prototype; the T-22. Two of the latter type were given to Hungary in 1941. The Hungarian engineers further extended the front armour to 50 mm and replaced the 47 mm gun with a 40 mm Škoda A17. The overall weight was also increased to over 18 tonnes.