Space Traveller Log, Part 2 (H-O)
All astronauts, cosmonauts and taikonauts in space
Last update: 9 August 2025
| Abbreviations | ASTP = Apollo-Soyuz Test Program | STS = Shuttle Transporter System | ISS = International Space Station | Pi = Pilot | MiSp = Mission Specialist (e.g. engineer, physician) |
| Note |
Suborbital spacecraft flights (Mercury MR-3 and MR-4) and inflight aborts (Soyuz 18A, Soyuz-T 10) of missions are counted. First time crew members in the Challenger catastrophe (C. McAuliffe, M. Smith) are listed as well, while Apollo 1 victim R. Chaffee is included for completeness, though not counted. Also not counted as space flights are purely suborbital tourist flights. All X-15 and SpaceShipOne test flights are recorded as suborbital astronaut wings flights, though. |
To select by family name, click a letter: A B C D E F G | H I J K L M N O | P Q R S T U V W X Y Z
| No. | Name | Year | Country | Total | Active service | Programme / | Space station(s) | Assignment / profession; |
|---|---|---|---|---|---|---|---|---|
| [first name (nickname) surname] | of birth | (nation) | flights | (from - to) | Spacecraft | visited | Remarks / mission events | |
| H | ↑ | |||||||
| Christopher Hadfield | 1959 | Canada | 3 | 1995 - 2013 | STS; Soyuz-TMA | Mir; ISS | MiSp | |
| Tyler (Nick) Hague | 1975 | USA | 3 | 2018 - | Soyuz-MS; Dragon | ISS | MiSp; Soyuz MS-10 launch abort | |
| Claudie Haigneré (André-Deshays) |
1957 | France | 2 | 1996 - 2001 | Soyuz-TM | Mir; ISS | MiSp | |
| Jean-Pierre Haigneré | 1948 | France | 2 | 1993 - 1999 | Soyuz-TM | Mir | MiSp | |
| Fred Haise | 1933 | USA | 1 | 1970 | Apollo | – | Pi; moon landing fails but Apollo 13 crew returns safely to Earth | |
| James Halsell | 1956 | USA | 5 | 1994 - 2000 | STS | Mir; ISS | Pi | |
| Kenneth Ham | 1964 | USA | 2 | 2008 - 2010 | STS | ISS | Pi | |
| Lloyd Hammond | 1952 | USA | 2 | 1991 - 1994 | STS | – | Pi | |
| Gregory Harbaugh | 1956 | USA | 4 | 1991 - 1997 | STS | Mir | MiSp | |
| Bernard Harris | 1956 | USA | 2 | 1993 - 1995 | STS | Mir | MiSp | |
| Terry Hart | 1946 | USA | 1 | 1984 | STS | – | MiSp | |
| Henry Hartsfield † | 1933 | USA | 3 | 1982 - 1985 | STS | – | Pi | |
| Frederick Hauck | 1941 | USA | 3 | 1983 - 1988 | STS | – | Pi | |
| Steven Hawley | 1951 | USA | 5 | 1984 - 1999 | STS | – | MiSp | |
| Susan Helms | 1958 | USA | 5 | 1993 - 2001 | STS | ISS | MiSp | |
| Karl Henize † | 1926 | USA | 1 | 1985 | STS | – | MiSp | |
| Thomas Hennen | 1952 | USA | 1 | 1991 | STS | – | MiSp | |
| Terence (Tom) Henricks | 1952 | USA | 4 | 1991 - 1996 | STS | – | Pi | |
| Miroslaw Hermaszewski | 1941 | Poland | 1 | 1978 | Soyuz | Salyut 6 | MiSp; second Interkosmos mission | |
| José Hernández | 1962 | USA | 1 | 2009 | STS | ISS | MiSp | |
| John Herrington | 1958 | USA | 1 | 2002 | STS | ISS | MiSp | |
| Richard Hieb | 1955 | USA | 3 | 1991 - 1994 | STS | – | MiSp | |
| Joan Higginbotham | 1964 | USA | 1 | 2006 | STS | ISS | MiSp | |
| David Hilmers | 1950 | USA | 4 | 1985 - 1992 | STS | – | MiSp | |
| Robert Hines | 1975 | USA | 1 | 2022 - | Dragon | ISS | Pi | |
| Yozo Hirano | 1985 | Japan | 1 | 2021 | Soyuz-MS | ISS | MiSp; tourist | |
| Kathryn Hire | 1959 | USA | 2 | 1998 - 2010 | STS | ISS | MiSp | |
| Charles Hobaugh | 1961 | USA | 3 | 2001 - 2009 | STS | ISS | Pi | |
| Warren Hoburg | 1985 | USA | 1 | 2023 - | Dragon | ISS | Pi | |
| Jeffrey Hoffman | 1944 | USA | 5 | 1985 - 1996 | STS | – | MiSp | |
| Michael Hopkins | 1968 | USA | 2 | 2013 - | Soyuz-TMA; Dragon | ISS | Pi & MiSp | |
| Scott (Doc) Horowitz | 1957 | USA | 4 | 1996 - 2001 | STS | ISS | Pi | |
| Akihito Hoshide | 1968 | Japan | 3 | 2008 - | STS; Soyuz-TMA; Dragon | ISS | MiSp | |
| Millie Hughes-Fulford | 1945 | USA | 1 | 1991 | STS | – | MiSp | |
| Douglas Hurley | 1966 | USA | 3 | 2009 - | STS; Dragon | ISS | Pi | |
| Rick Husband † | 1957 | USA | 2 | 1999 - 2003 | STS | ISS | Pi; died in shuttle Columbia re-entry accident (STS-107) | |
| I | ↑ | |||||||
| James Irwin † | 1930 | USA | 1 | 1971 | Apollo | – | Pi | |
| Jared Isaacman | 1983 | USA | 2 | 2021 | Dragon | – | MiSp/Pi | |
| Aleksandr Ivanchenkov | 1940 | Russia | 2 | 1978 - 1982 | Soyuz; Soyuz-T | Salyut 6 & 7 | MiSp | |
| Anatoli Ivanishin | 1969 | Russia | 3 | 2011 - | Soyuz-TMA/-MS | ISS | En | |
| Georgi Ivanov | 1940 | Bulgaria | 1 | 1979 | Soyuz | Salyut 6 | MiSp; fourth Interkosmos mission | |
| Marsha Ivins | 1951 | USA | 5 | 1990 - 2001 | STS | Mir; ISS | MiSp | |
| J | ↑ | |||||||
| Sigmund Jähn † | 1937 | Germany | 1 | 1978 | Soyuz | Salyut 6 | MiSp; first (East) German cosmonaut in space; third Interkosmos misson | |
| Gregory Jarvis † | 1944 | USA | 1 | 1986 | STS | – | MiSp; died in shuttle Challenger explosion (STS 51-L) | |
| Mae Jemison | 1956 | USA | 1 | 1992 | STS | – | MiSp | |
| Tamara Jernigan | 1959 | USA | 5 | 1991 - 1999 | STS | ISS | MiSp | |
| Brent Jett | 1958 | USA | 4 | 1996 - 2006 | STS | Mir; ISS | Pi | |
| Jiang Xinlin | 1988 | China | 1 | 2023 - | Shenzhou | TSS | Pi | |
| Jing Haipeng | 1966 | China | 4 | 2008 - | Shenzhou | Tiangong 1 & 2; TSS | Pi | |
| Gregory C. Johnson | 1954 | USA | 1 | 2009 | STS | ISS | Pi | |
| Gregory H. Johnson | 1962 | USA | 2 | 2008 - 2011 | STS | ISS | Pi | |
| Thomas Jones | 1955 | USA | 4 | 1994 - 2001 | STS | ISS | MiSp | |
| K | ↑ | |||||||
| Leonid Kadenyuk | 1951 | Ukraine | 1 | 1997 | STS | – | Pi & MiSp | |
| Aleksandr Kaleri | 1956 | Russia | 5 | 1992 - 2011 | Soyuz-TM/-TMA | Mir; ISS | MiSp | |
| Norishige Kanai | 1976 | Japan | 1 | 2017 - | Soyuz-MS | ISS | MiSp | |
| Tibor Kapu | 1991 | Hungary | 1 | 2025 - | Dragon | ISS | MiSp | |
| Janet Kavandi | 1959 | USA | 3 | 1998 - 2001 | STS | Mir; ISS | MiSp; member of final Shuttle/Mir mission | |
| James (Vegas) Kelly | 1964 | USA | 2 | 2001 - | STS | ISS | Pi | |
| Mark Kelly | 1964 | USA | 4 | 2001 - 2011 | STS | ISS | Pi | |
| Scott Kelly | 1964 | USA | 4 | 1999 - 2016 | STS; Soyuz-TMA | ISS | Pi | |
| Joseph Kerwin | 1932 | USA | 1 | 1973 | Apollo/Skylab 2 | Skylab-1 | Pi | |
| Yevgeni Khrunov † | 1933 | Russia | 1 | 1969 | Soyuz | – | Pi; docking with another Soyuz spacecraft | |
| Anna Kikina | 1984 | Russia | 1 | 2022 - | Dragon | ISS | MiSp | |
| Susan Kilrain (Still) | 1961 | USA | 2 | 1997 | STS | – | Pi | |
| Jonny Kim | 1984 | USA | 1 | 2025 - | Soyuz-MS | ISS | MiSp | |
| Robert Kimbrough | 1967 | USA | 3 | 2008 - | STS; Soyuz-MS; Dragon | ISS | MiSp | |
| Leonid Kizim | 1941 | Ukraine | 3 | 1980 - 1986 | Soyuz-T | Salyut 6 & 7; Mir | Pi | |
| Pyotr Klimuk | 1942 | Belorus | 3 | 1973 - 1978 | Soyuz | Salyut 4 & 6 | Pi | |
| Christina Koch | 1979 | USA | 1 | 2019 - | Soyuz-MS | ISS | MiSp | |
| Vladimir Komarov † | 1927 | Russia | 2 | 1964 - 1967 | Voskhod; Soyuz | – | Pi; Soyuz 1 crashed at landing, killing the single cosmonaut | |
| Yelena Kondakova | 1957 | Russia | 2 | 1994 - 1997 | Soyuz-TM; STS | Mir | MiSp | |
| Dimitri Kondratyev | 1969 | Russia | 1 | 2010/11 | Soyuz-TMA | ISS | Pi | |
| Oleg Kononenko | 1964 | Ukraine | 5 | 2008 - | Soyuz-TMA/-MS | ISS | Pi | |
| Timothy Kopra | 1963 | USA | 2 | 2009 - 2016 | STS; Soyuz-TMA | ISS | MiSp | |
| Mikhail Korniyenko | 1960 | Russia | 2 | 2010 - | Soyuz-TMA | ISS | MiSp | |
| Sergey Korsakov | 1984 | Russia | 1 | 2022 - | Soyuz-MS | ISS | En | |
| Valeri Korzun | 1953 | Russia | 2 | 1996 - 2002 | Soyuz-TM; STS | Mir; ISS | Pi & MiSp | |
| Oleg Kotov | 1965 | Russia | 3 | 2007 - | Soyuz-TMA | ISS | MiSp | |
| Vladimir Kovalyonok | 1942 | Belorus | 3 | 1977 - 1981 | Soyuz; Soyuz-T | Salyut 6 | Pi | |
| Konstantin Kozeyev | 1967 | Russia | 1 | 2001 | Soyuz-TM | ISS | MiSp | |
| Kevin Kregel | 1956 | USA | 4 | 1995 - 2000 | STS | – | Pi | |
| Sergei Krikalyov | 1958 | Russia | 6 | 1988 - 2005 | Soyuz-TM/-TMA; STS | Mir; ISS | MiSp; member of the first ISS Expedition Crew | |
| Valeri Kubasov | 1935 | Russia | 3 | 1969 - 1980 | Soyuz; ASTP | Salyut 6 | MiSp | |
| Sergey Kud-Sverchkov | 1983 | Russia | 1 | 2020 - | Soyuz-MS | ISS | En | |
| André Kuipers | 1958 | Netherlands | 2 | 2004 - 2012 | Soyuz-TMA | ISS | MiSp | |
| L | ↑ | |||||||
| Guy Laliberté | 1959 | Cannda | 1 | 2009 | Soyuz-TMA | ISS | Space tourist | |
| Aleksandr Laveykin | 1951 | Russia | 1 | 1987 | Soyuz-TM | Mir | MiSp | |
| Wendy Lawrence | 1959 | USA | 4 | 1995 - 2005 | STS | Mir; ISS | MiSp | |
| Vasili Lazarev † | 1928 | Russia | 2 | 1973 - 1975 | Soyuz | – | MiSp | |
| Aleksandr Lazutkin | 1957 | Russia | 1 | 1997 | Soyuz-TM | Mir | MiSp | |
| Valentin Lebedev | 1942 | Russia | 2 | 1973 - 1982 | Soyuz; Soyuz-T | Salyut 7 | MiSp | |
| Mark Lee | 1952 | USA | 4 | 1989 - 1997 | STS | – | MiSp | |
| David Leestma | 1949 | USA | 3 | 1984 - 1992 | STS | – | MiSp | |
| William Lenoir | 1939 | USA | 1 | 1982 | STS | – | MiSp | |
| Aleksei Leonov † | 1934 | Russia | 2 | 1965 - 1975 | Voskhod; Soyuz; ASTP | – | Pi | |
| Fred Leslie | 1951 | USA | 1 | 1995 | STS | – | MiSp | |
| Anatoli Levchenko † | 1941 | Ukraine | 1 | 1987 | Soyuz-TM | Mir | Pi | |
| Li Cong | 1989 | China | 1 | 2024 - | Shenzou | TSS | Pi | |
| Li Guangsu | 1987 | China | 1 | 2024 - | Shenzou | TSS | Pi | |
| Byron Lichtenberg | 1948 | USA | 2 | 1983 - 1992 | STS | – | MiSp | |
| Don Lind | 1930 | USA | 1 | 1985 | STS | – | MiSp | |
| Kjell Lindgren | 1973 | USA | 2 | 2015 - | Soyuz-TMA; Dragon | ISS | MiSp | |
| Steven Lindsey | 1960 | USA | 5 | 1997 - 2011 | STS | ISS | Pi | |
| Jerry Linenger | 1955 | USA | 2 | 1994 - 1997 | STS | Mir | MiSp | |
| Richard Linnehan | 1957 | USA | 4 | 1996 - 2008 | STS | – | MiSp | |
| Gregory Linteris | 1957 | USA | 2 | 1997 | STS | – | MiSp | |
| Liu Boming | 1966 | China | 1 | 2008 - | Shenzhou | – | Pi | |
| Liu Wang | 1969 | China | 2 | 2012 - | Shenzhou | Tiangong 1, TSS | Pi | |
| Liu Yang | 1978 | China | 1 | 2012 - | Shenzhou | Tiangong 1 | MiSp; first female taikonaut | |
| Paul Lockhart | 1956 | USA | 2 | 2002 | STS | ISS | Pi | |
| Yuri Lonchakov | 1965 | Russia | 3 | 2001 - 2009 | STS; Soyuz-TMA | ISS | MiSp | |
| Michael López-Alegría | 1958 | USA | 6 | 1995 - 2024 | STS; Dragon | ISS | MiSp; Pi | |
| John (Mike) Lounge | 1946 | USA | 3 | 1985 - 1990 | STS | – | MiSp | |
| Jack Lousma | 1936 | USA | 2 | 1973 - 1982 | Apollo/Skylab 3; STS | Skylab-1 | Pi | |
| Stanley Love | 1965 | USA | 1 | 2008 | STS | ISS | MiSp | |
| James Lovell † | 1928 | USA | 4 | 1965 - 1970 | Gemini; Apollo | – | Pi; moon landing fails but Apollo 13 crew returns safely to Earth | |
| George Low † | 1956 | USA | 3 | 1990 - 1993 | STS | – | MiSp | |
| Edward Lu | 1963 | USA | 3 | 1997 - 2000 | STS; Soyuz-TMA | Mir; ISS | MiSp | |
| Shannon Lucid | 1943 | USA | 5 | 1985 - 1996 | STS | Mir | MiSp | |
| Vladimir Lyakhov † | 1941 | Russia | 3 | 1979 - 1988 | Soyuz; Soyuz-T/-TM | Salyut 6 & 7; Mir | Pi | |
| M | ↑ | |||||||
| Steven MacLean | 1954 | Canada | 2 | 1992 - 2006 | STS | ISS | MiSp | |
| Yusaku Maezawa | 1975 | Japan | 1 | 2021 - | Soyuz-MS | ISS | MiSp; tourist | |
| Sandra Magnus | 1964 | USA | 3 | 2002 - 2011 | STS | ISS | MiSp | |
| Oleg Makarov † | 1933 | Russia | 4 | 1973 - 1980 | Soyuz; Soyuz-T | Salyut 6 | MiSp | |
| Yuri Malenchenko | 1961 | Ukraine | 6 | 1994 - 2016 | Soyuz-TM/-TMA; STS | Mir; ISS | Pi | |
| Franco Malerba | 1946 | Italy | 1 | 1992 | STS | – | MiSp | |
| Yuri Malyshev † | 1941 | Russia | 2 | 1980 - 1984 | Soyuz-T | Salyut 6 & 7 | Pi | |
| Gennadi Manakov | 1950 | Russia | 2 | 1990 - 1993 | Soyuz-TM | Mir | Pi | |
| Musa Manarov | 1951 | Azerbaijan | 2 | 1987 - 1990 | Soyuz-TM | Mir | MiSp | |
| Nicole Mann | 1977 | USA | 1 | 2022 - | Dragon | ISS | Pi | |
| Thomas Marshburn | 1960 | USA | 3 | 2009 - | STS; Soyuz-TMA; Dragon | ISS | MiSp | |
| Michael Massimino | 1962 | USA | 2 | 2002 - 2009 | STS | – | MiSp | |
| Richard Mastracchio | 1960 | USA | 4 | 2000 - | STS; Soyuz-TMA | ISS | MiSp | |
| Thomas (Ken) Mattingly † | 1936 | USA | 3 | 1972 - 1985 | Apollo; STS | – | MiSp | |
| Denis Matveev | 1983 | Russia | 1 | 2022 - | Soyuz-MS | ISS | En | |
| Matthias Maurer | 1970 | Germany | 1 | 2021 - | Dragon | ISS | MiSp | |
| Megan McArthur | 1971 | USA | 2 | 2009 - | STS; Dragon | ISS | MiSp | |
| William McArthur | 1951 | USA | 4 | 1993 - 2006 | STS; Soyuz-TMA | Mir; ISS | MiSp | |
| Sharon Christa McAuliffe † | 1948 | USA | 1 | 1986 | STS | – | MiSp; died in shuttle Challenger explosion (STS 51-L) | |
| Jon McBride | 1943 | USA | 1 | 1984 | STS | – | Pi | |
| Bruce McCandless † | 1937 | USA | 2 | 1984 - 1990 | STS | – | MiSp | |
| Anne McClain | 1979 | USA | 2 | 2018 - | Soyuz-MS; Dragon | ISS | Pi & MiSp | |
| William McCool † | 1961 | USA | 1 | 2003 | STS | – | Pi; died in shuttle Columbia re-entry accident (STS-107) | |
| Michael McCulley | 1943 | USA | 1 | 1989 | STS | – | Pi | |
| James McDivitt | 1929 | USA | 2 | 1965 - 1969 | Gemini; Apollo | – | Pi | |
| Donald McMonagle | 1952 | USA | 3 | 1991 - 1994 | STS | – | Pi | |
| Ronald McNair † | 1950 | USA | 2 | 1984 - 1986 | STS | – | MiSp; died in shuttle Challenger explosion (STS 51-L) | |
| Carl Meade | 1950 | USA | 3 | 1990 - 1994 | STS | – | MiSp | |
| Jessica Meir | 1977 | USA | 1 | 2019 - | Soyuz-MS | ISS | MiSp | |
| Bruce Melnick | 1949 | USA | 2 | 1990 - 1992 | STS | – | MiSp | |
| Pamela Melroy | 1961 | USA | 2 | 2000 - 2007 | STS | ISS | Pi | |
| Leland Melvin | 1964 | USA | 2 | 2008 - 2009 | STS | ISS | MiSp | |
| Anna Menon | 1985 | USA | 1 | 2024 | Dragon | – | MiSp | |
| Ulf Merbold | 1941 | Germany | 3 | 1983 - 1994 | STS; Soyuz-TM | Mir | MiSp | |
| Ernst Messerschmid | 1945 | Germany | 1 | 1985 | STS | – | MiSp | |
| Dorothy Metcalf-Lindenburger | 1975 | USA | 1 | 2010 | STS | ISS | MiSp | |
| Jannicke Mikkelsen | 1986 | Norway | 1 | 2025 | Dragon | – | Pi & MiSp | |
| Aleksandr Misurkin | 1977 | Russia | 3 | 2013 - | Soyuz-TMA/-MS | ISS | MiSp | |
| Edgar Mitchell † | 1930 | USA | 1 | 1971 | Apollo | – | Pi | |
| Andreas Mogensen | 1976 | Denmark | 2 | 2015 - | Soyuz-TMA; Dragon | ISS | MiSp | |
| Jasmin Moghbeli | 1983 | USA | 1 | 2023 - | Dragon | ISS | Pi | |
| Abdul Mohmand | 1959 | Afghanistan | 1 | 1988 | Soyuz-TM | Mir | MiSp | |
| Mamoru Mohri | 1948 | Japan | 2 | 1992 - 2000 | STS | – | MiSp | |
| Andrew Morgan | 1976 | USA | 1 | 2019 - | Soyuz-MS | ISS | MiSp | |
| Barbara Morgan | 1951 | USA | 1 | 2007 | STS | ISS | MiSp | |
| Lee Morin | 1952 | USA | 1 | 2002 | STS | ISS | MiSp | |
| Boris Morukov † | 1950 | Russia | 1 | 2000 | STS | ISS | MiSp | |
| Chiaki Mukai | 1952 | Japan | 2 | 1994 - 1998 | STS | – | MiSp; first Japanese woman in space | |
| Richard (Mike) Mullane | 1945 | USA | 3 | 1984 - 1990 | STS | – | MiSp | |
| Talgat Musabayev | 1951 | Kazakhstan | 3 | 1994 - 2001 | Soyuz-TM | Mir; ISS | MiSp | |
| Franklin (Story) Musgrave | 1935 | USA | 6 | 1983 - 1996 | STS | – | MiSp | |
| Sheikh Muszaphar Shukor | 1972 | Malaysia | 1 | 2007 | Soyuz-TMA | ISS | MiSp | |
| N | ↑ | |||||||
| Steven Nagel | 1946 | USA | 4 | 1985 - 1993 | STS | – | Pi | |
| Clarens (Bill) Nelson | 1942 | USA | 1 | 1986 | STS | – | MiSp; then US Congressman | |
| George (Pinky) Nelson | 1950 | USA | 3 | 1984 - 1988 | STS | – | MiSp | |
| Rodolfo Neri Vela | 1952 | Mexico | 1 | 1985 | STS | – | MiSp | |
| Paolo Nespoli | 1957 | Italy | 3 | 2007 - 2017 | STS; Soyuz-TMA/-MS | ISS | MiSp | |
| James Newman | 1956 | USA | 4 | 1993 - 2002 | STS | ISS | MiSp | |
| Claude Nicollier | 1944 | Switzerland | 4 | 1992 - 1999 | STS | – | MiSp | |
| Nie Haisheng | 1964 | China | 2 | 2005 - | Shenzhou | Tiangong 1 | Pi | |
| Andrian Nikolayev † | 1929 | Russia | 2 | 1962 - 1970 | Vostok; Soyuz | – | Pi | |
| Soichi Noguchi | 1965 | Japan | 3 | 2005 - | STS; Soyuz-TMA; Dragon | ISS | MiSp | |
| Carlos Noriega | 1959 | USA | 2 | 1997 - 2000 | STS | Mir; ISS | MiSp | |
| Lisa Nowak | 1963 | USA | 1 | 2006 | STS | ISS | MiSp | |
| Oleg Novitskiy | 1971 | Russia | 4 | 2013 - | Soyuz-TMA/-MS | ISS | MiSp | |
| Karen Nyberg | 1969 | USA | 2 | 2008 - | STS; Soyuz-TMA | ISS | MiSp | |
| O | ↑ | |||||||
| Ellen Ochoa | 1958 | USA | 4 | 1993 - 2002 | STS | ISS | MiSp | |
| Wubbo Ockels | 1946 | Netherlands | 1 | 1985 | STS | – | MiSp | |
| Bryan O'Connor | 1946 | USA | 2 | 1985 - 1991 | STS | – | Pi | |
| William (Bill) Oefelein | 1965 | USA | 1 | 2006 | STS | ISS | Pi | |
| Loral O'Hara | 1983 | USA | 1 | 2023 - | Soyuz-MS | ISS | MiSp | |
| John Olivas | 1965 | USA | 2 | 2007 - 2009 | STS | ISS | MiSp | |
| Gregory Olsen | 1945 | USA | 1 | 2005 | Soyuz-TMA | ISS | MiSp; third paying space tourist | |
| Takuya Onishi | 1975 | Japan | 2 | 2016 - | Soyuz-MS; Dragon | ISS | MiSp | |
| Ellison Onizuka † | 1946 | USA | 2 | 1985 - 1986 | STS | – | MiSp; died in shuttle Challenger explosion (STS 51-L) | |
| Yuri Onufrienko | 1961 | Ukraine | 2 | 1996 - 2002 | Soyuz-TM; STS | Mir; ISS | MiSp | |
| Stephen Oswald | 1951 | USA | 3 | 1992 - 1995 | STS | – | Pi | |
| Aleksey Ovchinin | 1971 | Russia | 3 | 2016 - | Soyuz-TMA/-MS | ISS | Pi; Soyuz MS-10 launch abort | |
| Robert Overmyer † | 1936 | USA | 2 | 1982 - 1985 | STS | – | Pi | |