Georgy Dobrovolsky

Georgiy Timofeyevich Dobrovolsky (Russian: Гео́ргий Тимофе́евич Доброво́льский; June 1, 1928 – June 30, 1971) was a Soviet cosmonaut who served on the three-man crew of the Soyuz 11 spacecraft. They became the world's first space station crew aboard Salyut 1, but died in space due to asphyxiation due to an accidentally opened valve. They were the first and, as of 2018, the only humans to have died in space.

Biography from Launch Library 2.

• Soyuz | Soyuz 11 — Commander · Success · June 6, 1971 · 04:55 UTC