Gregory Errol Chamitoff (born 6 August 1962 in Montreal, Quebec, Canada) is an engineer and NASA astronaut. He was assigned to Expedition 17 and flew to the International Space Station on STS-124, launching 31 May 2008. He was in space 198 days, joining Expedition 18 after Expedition 17 left the station, and returned to Earth 30 November 2008 on STS-126. Chamitoff served as a mission specialist on the STS-134 mission, which was the last flight of Endeavour and delivered the Alpha Magnetic Spectrometer.