Leonov was also known as an author and painter, with some of his works used on Soviet postage stamps.
Astronauts aboard the ISS plan to conduct eight more spacewalks in the coming three months, a record cadence since the assembly of the space station was completed in 2011, according to NASA.
Leonov - described by the Russian Space Agency as Cosmonaut No. 11 - was an icon both in his country as well as in the US.
In July 1975, he attended the first joint docking of a Soviet and foreign spacecraft, the Soyuz-19 and the US Apollo 18.More news: MSNBC news reporter interrupted by her child while presenting live on air
Leonov was twice awarded the Hero of the Soviet Union title. The two remained lifelong friends after the mission, and Apollo-Soyuz set the stage for later cooperation between the two Cold War superpowers in the subsequent Shuttle-Mir program and the International Space Station.
Leonov recounted the attractive and harrowing experience of his spacewalk mission in the book Two Sides of the Moon, co-written with NASA Apollo astronaut David Scott. That cooperation in space has continued, despite challenges in worldwide politics, to this day aboard the ISS.
Leonov trained as a military pilot before becoming a cosmonaut.
Kononenko spoke fondly of the Soviet space pioneer, saying he was a frequent guest at send-off ceremonies for space crews in Star City and at the cosmodrome in Baikonur, Kazakhstan.More news: Several people stabbed at United Kingdom shopping centre
"This is a loss for the whole planet", said Russian cosmonaut Oleg Kononenko.
Messages of condolences poured in from around the globe following news of his death.
Earlier this year, two Russian cosmonauts honored Leonov on his 85th birthday.
"His venture into the vacuum of space began the history of extravehicular activity that makes today's @Space_Station maintenance possible", NASA said on Twitter.More news: 'Jesus Shoes' filled with holy water sold out in minutes
Leonov will be laid to rest at a cemetery just outside Moscow on Tuesday.
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