This may not be one of the most visited graves per se, but it must, after Serge Gainsbourg's, be the most enthusiastically visited grave in the cemetery, which I find slightly odd, although I certainly welcome such interest in an experimental, strongly left-wing writer. Wanna pull this one too, Google?
Julio Cortázar (1914–84) was born in Ixelles, Belgium, and was an Argentine writer whose family returned to Buenos Aires in 1918. His introduction to surrealism came from reading Jean Cocteau's Opium. He emigrated to France (where he worked as a translator for UNESCO) in 1951 to escape Perón's regime, and stayed there until his death. He supported revolutionary Cuba, and the sandinistas in Nicaragua, but refused the invitation to join Oulipo as it is an apolitical organisation.
Cortázar became a French national in 1981. His most famous work is the experimental novel Rayuela, published in Spain in 1963 and translated as Hopscotch in English in 1966 and the same year as Marelle in French.
My first – and very long – post on the Cimetière du Montparnasse:
Montparnasse Cemetery / Cimetière du Montparnasse