Alexei Leonov, the first human to walk in space 54 years ago, has died in Moscow aged 85.
Russian space agency Roscosmos confirmed his death in a statement on its website, but gave no further details.
Mr Leonov performed his spacewalk on March 18, 1965, when he exited his Voskhod 2 capsule, secured by a tether.
On his second trip to space 10 years later, Mr Leonov commanded the Soviet half of the Apollo-Soyuz 19 mission.
It was the first joint space mission between the Soviet Union and the United States, carried out at the height of the Cold War.
Days before his 85th birthday in May, two Russian crew members on the International Space Station ventured into open space on a planned spacewalk with stickers attached to their spacesuits paying tribute to Mr Leonov, and congratulated him from space.
Roscosmos said Mr Leonov’s funeral will take place on Tuesday at a military cemetery outside Moscow.