Scott Joseph Kelly (born February 21, 1964; CAPT, USN, Ret.) is an engineer, retired American astronaut, and a retired U.S. Navy Captain). A veteran of four space flights, Kelly commanded the International Space Station (ISS) on Expeditions 26, 45, and 46.

Kelly's first spaceflight was as pilot of, during STS-103 in December 1999. This was the third servicing mission to the Hubble Space Telescope, and lasted for just under eight days. Kelly's second spaceflight was as mission commander of STS-118, a 12-day Space Shuttle mission to the International Space Station in August 2007. Kelly's third spaceflight was as a crewmember on Expedition 25/26 on the ISS. He arrived at the ISS aboard Soyuz TMA-01M on 9 October 2010, and served as a flight engineer until he took over command of the station on 25 November 2010 at the start of Expedition 26. Expedition 26 ended on 16 March 2011 with the departure of Soyuz TMA-01M.

In November 2012, Kelly and Russian cosmonaut Mikhail Korniyenko were selected for a year-long mission to the International Space Station. Their year in space began with the launch of Soyuz TMA-16M on March 27, 2015, and they remained on the station for Expeditions 43, 44, 45 and 46. The year-long mission ended on March 1, 2016 with the departure of Soyuz TMA-18M from the station.

After his final flight, Kelly had spent 520 days in space, the most by an American astronaut. This record has since been broken by astronauts Jeff Williams (534 days) and Peggy Whitson (665 days). Kelly's identical twin brother, Mark Kelly, is a former astronaut. The Kelly brothers are the only siblings to have travelled in space. On March 12, 2016, Kelly announced his retirement for April 2016.

• From https://en.wikipedia.org/wiki/Scott_Kelly_(astronaut)_, accessed 13 February 2019.