Soyuz 1 (Russian: Союз 1, Union 1) was a manned spaceflight of the Soviet Space Programme. Launched into orbit on April 23, 1967 carrying cosmanut Colonel Vladimir Komarov Soyuz 1 was the first flight of the Soyuz Spacecraft The mission plan was complex, involving a rendezvous with Soyuz - 2, swapping crew members before returning to Earth.

Soyuz 1 was plagued with technical issues, and Komarov was killed when the spacecraft crashed during its return to Earth. This was the first in-flight fatality in the history of spaceflight.

Soyuz (Russian: Союз, IPA: [sɐˈjus], lit. 'Union') is a series of spacecraft which has been in service since the 1960s, having made more than 140 flights. It was designed for the Soviet space program by the Korolev Design Bureau (now Energia). The Soyuz succeeded the Voskhod spacecraft and was originally built as part of the Soviet crewed lunar programs. It is launched on a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan. Between the 2011 retirement of the Space Shuttle and the 2020 demo flight of SpaceX Crew Dragon, the Soyuz served as the only means to make crewed space flights and to reach the International Space Station, for which it remains heavily used.

The first Soyuz flight was uncrewed and started on 28 November 1966. The first Soyuz mission with a crew, Soyuz 1, launched on 23 April 1967 but ended with a crash due to a parachute failure, killing cosmonaut Vladimir Komarov. The following flight was uncrewed. Soyuz 3, launched on 26 October 1968, became the program's first successful crewed mission. The only other flight to suffer a fatal accident, Soyuz 11, killed its crew of three when the cabin depressurized just before reentry. These are the only humans to date who are known to have died above the Kármán line. Despite these early incidents, Soyuz is widely considered the world's safest, most cost-effective human spaceflight vehicle, established by its unparalleled length of operational history. Soyuz spacecraft were used to carry cosmonauts to and from Salyut and later Mir Soviet space stations, and are now used for transport to and from the International Space Station (ISS). At least one Soyuz spacecraft is docked to ISS at all times for use as an escape craft in the event of an emergency. The spacecraft is intended to be replaced by the six-person Orel spacecraft.