Kosmos 37 (Russian: Космос 37 meaning Cosmos 37) or Zenit-2 No.21 was a Soviet, first generation, low resolution, optical film-return reconnaissance satellite launched in 1964.

A Zenit-2 spacecraft, Kosmos 37 was the twentieth of eighty-one such satellites to be launched[3] and had a mass of 4,730 kilograms (10,430 lb).

Kosmos 37 was launched by a Vostok-2 rocket, serial number R15001-04,[4] flying from Site 31/6 at the Baikonur Cosmodrome.

[6] During the mission one of the satellite's film reels snapped, resulting in the associated camera only taking some of the images it had been programmed to produce.

[8] On 22 August 1964, after eight days in orbit, Kosmos 37 was deorbited with its return capsule descending by parachute for recovery by Soviet forces.