Sigmund Werner Paul Jähn (born 13 February 1937) is a German cosmonaut and pilot, who in 1978 became the first German to fly in space as part of the Soviet Union's Interkosmos programme.

Jing Haipeng (simplified Chinese: 景海鹏; traditional Chinese: 景海鵬; pinyin: Jǐng Hǎipéng; born October 24, 1966) is a Chinese pilot and astronaut selected as part of the Shenzhou program. A fighter pilot in the People's Liberation Army Air Force, he was selected to be a CNSA astronaut in 1998. He is the first Chinese astronaut to have flown on three missions: Shenzhou 7, Shenzhou 9 and Shenzhou 11.

Zenon Jankowski is a retired Polish pilot, colonel of the Polish Army and cosmonaut. Jankowski was selected as backup cosmonaut of the 1st Polish cosmonaut Mirosław Hermaszewski for the Soyuz 30 mission in 1978.

Leonid Kostyantynovych Kadenyuk (Ukrainian: Леонід Костянтинович Каденюк, 28 January 1951 – 31 January 2018) was the first astronaut of independent Ukraine. He flew on NASA's Space Shuttle Columbia in 1997 as part of the international mission STS-87.

Aleksandr Yuriyevich "Sasha" Kaleri (Russian: Александр Юрьевич Калери; born Jūrmala, Latvian SSR, USSR, 13 May 1956) is a Russian cosmonaut and veteran of extended stays on the Mir Space Station and the International Space Station (ISS). Kaleri has most recently been in space aboard the ISS serving as a flight engineer for the long duration Expedition 25/26 missions. He has spent the fourth-longest time in space of any person, the longest time in space of any currently active cosmonaut, and the longest time in space of any person not born in what is now Russia.

Yevgeni Vassilyevich Khrunov (Russian: Евге́ний Васи́льевич Хруно́в; September 10, 1933 – May 20, 2000) was a Soviet cosmonaut who flew on the Soyuz 5/Soyuz 4 mission.

Leonid Denisovich Kizim (Кизим Леонид Денисович) (August 5, 1941 – June 14, 2010) was a Soviet cosmonaut. He was selected as a cosmonaut on October 23, 1965. Kizim flew as Commander on Soyuz T-3, Soyuz T-10 and Soyuz T-15, and also served as backup commander for Soyuz T-2. All together he spent 374 days 17 hours 56 minutes in space. On Soyuz T-15, he was part of the only crew to visit two space stations on one spaceflight (Mir and Salyut 7).

Pyotr Ilyich Klimuk (Belarusian: Пётр Ільіч Кліму́к; Russian: Пётр Ильич Климу́к; born 10 July 1942) is a former Soviet cosmonaut and the first Belarusian to perform space travel. Klimuk made three flights into space. Klimuk attended the Leninski Komsomol Chernigov High Aviation School and entered the Soviet Air Force in 1964. The following year, he was selected to join the space programme. His first flight was a long test flight on Soyuz 13 in 1973. This was followed by a mission to the Salyut 4 space station on Soyuz 18 in 1975. From 1976 he became involved in the Intercosmos and made his third and final spaceflight on an Intercosmos flight with Polish cosmonaut Mirosław Hermaszewski on Soyuz 30.

Pyotr Ivanovich Kolodin (Russian: Пётр Иванович Колодин; (born September 23, 1930) is a former Soviet cosmonaut. Although he retired in 1983 without flying in space, Kolodin served non-flying assignments on several spaceflights.

Vladimir Mikhaylovich Komarov (Russian: Влади́мир Миха́йлович Комаро́в, IPA: [vlɐˈdʲimʲɪr mʲɪˈxaɪləvʲɪtɕ kəmɐˈrof]; 16 March 1927 – 24 April 1967) was a Soviet test pilot, aerospace engineer and cosmonaut. In October 1964, he commanded Voskhod 1, the first spaceflight to carry more than one crew member. He became the first cosmonaut to fly in space twice when he was selected as the solo pilot of Soyuz 1, the first manned test flight of a new spacecraft. A parachute failure caused his Soyuz capsule to crash into the ground after re-entry on 24 April 1967, making him the first human to die in a space flight.

Yelena Vladimirovna Kondakova (Russian: Елена Владимировна Кондакóва; born March 30, 1957) was the third Soviet/Russian female cosmonaut to travel to space and the first woman to make a long-duration spaceflight. Her first trip into space was on Soyuz TM-20 on October 4, 1994. She returned to Earth on March 22, 1995 after a five-month stay at the Mir space station. Kondakova's second flight was as a mission specialist on the United States Space Shuttle Atlantis during mission STS-84 in May 1997. She was the last Russian female in space until her successor cosmonaut Elena Serova flew to the International Space Station (ISS) on 25 September 2014.

Dmitri Yur'yevich Kondrat'yev Russian: Дмитрий Юрьевич Кондратьев (born 25 May 1969 in Irkutsk, Russia) is a retired Russian cosmonaut. He served as a crewmember on the International Space Station long duration mission Expedition 27 as Commander, having also served as a Flight Engineer on Expedition 26 during the same stay in space. Kondratyev traveled to space for the first time aboard the Soyuz TMA-20 spacecraft in December 2010.