Kosmos 18 (Russian: Космос 18 meaning Cosmos 18) or Zenit-2 No.11 was a Soviet optical film-return reconnaissance satellite launched in 1963.

A Zenit-2 satellite, Kosmos 18 was the eleventh of eighty-one such spacecraft to be launched.

In addition to reconnaissance, it was also used for research into radiation in support of the Vostok programme.

Its return capsule descended under parachute and was recovered by the Soviet forces in the steppe in Kazakhstan.

[4] In addition to its imaging mission, Kosmos 18 was used to conduct measurements of radiation levels in low Earth orbit.