Georgy Mikhaylovich Grechko (Russian: Гео́ргий Миха́йлович Гре́чко; born May 25, 1931) is a retired Soviet cosmonaut who flew on several space flights including Soyuz 17, Soyuz 26, and Soyuz T-14.

Grechko graduated from the Leningrad Institute of Mechanics with a doctorate in mathematics. He was a member of Communist Party of the Soviet Union. He went on to work at Sergei Korolev's design bureau and from there was selected for cosmonaut training for the Soviet moon programme. When that program was cancelled, he went on to work on the Salyut space stations.

Grechko made the first spacewalk in an Orlan space suit on December 20, 1977 during the Salyut 6 EO-1 mission.

He was twice awarded the medal of Hero of the Soviet Union.

He resigned from the space programme in 1992 to lecture on atmospheric physics at the Russian Academy of Sciences. Grechko has written his memoirs as "Космонавт No. 34: От лучины до пришельцев," (Cosmonaut No. 34 From Splinter to Aliens) Olma Media Grupp, Moscow, 2013.

A minor planet 3148 Grechko discovered by Soviet astronomer Nikolai Stepanovich Chernykh in 1979 is named after him.

Grechko, along with Alexey Leonov, Vitaly Sevastyanov and Rusty Schweickart established the Association of Space Explorers in 1984. Membership is open to all people who have flown in outer space.