Ivan Dashev Radoev was a lyrical poet and playwright from Bulgaria.

Ivan Radunsky played the part of Bim in the clown duo of Bim Bom. He was the founder of that duo.

Ivan Gerasimovich Rakhmaninov was a Russian publisher, translator and educator.

Ivan Reis is a Brazilian comics artist. He is known for his work on comic books such as Dark Horse Comics' Ghost, Marvel Comics' Captain Marvel and Avengers Icons: The Vision and DC Comics' Action Comics, Green Lantern and Aquaman series. According to collaborator Geoff Johns, Reis's drawing style resembles those of Alan Davis and Neal Adams.

Ivan Pavlovich Rosly was a Soviet Army lieutenant general and a Hero of the Soviet Union who held division, army and corps command during World War II.

Ivan Sergeyevich Rukavishnikov was a Russian Silver Age symbolist poet, writer, playwright and translator from Ukrainian language.

Ivan Petrovich Sakharov was a Russian folklorist, ethnographer, archeologist and paleographer.

Ivan Sarailiev was a Bulgarian philosopher related to the school of pragmatism.; he finished his major book Pragmatism in 1938 quoting from Charles Sanders Peirce’s Collected Papers. Sarailiev was the first pragmatist in Eastern Europe and also a "very early pragmatist". He also introduced the idea of implied reader in his reception theory as early as in Savremennata nauka y religiata (1931).

Doctor Ivan Mikhaylovich Sechenov, was a Russian psychologist, physiologist, and medical scientist.

Ivan Innokentyevich Serebrennikov was a Russian statesman and Siberian regionalist. He served as Chairman of the Administrative Council of the Siberian Republic from 3rd September to 3rd November 1918 and Minister of Supply for the Russian State from 18 November to 27 December 1918.