Zond was the name given to two distinct series of Soviet robotic spacecraft launched between 1964 and 1970. The first series, based on the 3MV planetary probe, was intended to gather information about nearby planets.

The 3MV planetary probe is a designation for a common design used by early Soviet unmanned probes to Mars and Venus. It was an incremental improvement of earlier 2MV probes and was used for Zond 1, Zond 2 and Zond 3 missions to Mars as well as several Venera probes. It was standard practice of the Soviet space program to use standardized components as much as possible. All probes shared the same typical characteristics and differed usually in equipment necessary for specific missions. Each probe also incorporated improvements based on experience with earlier missions.