René de Saussure (17 March 1868 – 2 December 1943) was a Swiss Esperantist and professional mathematician who composed important works about Esperanto and interlinguistics from a linguistic viewpoint.

René's father was the scientist Henri Louis Frédéric de Saussure.

He developed the concept of neceso kaj sufiĉo ("necessity and sufficience") by which he opposed the criticism of Louis Couturat that Esperanto lacks recursion.

He later became a consultant for the International Auxiliary Language Association, the linguistic research body that standardized and presented Interlingua.

A new silver Esperanto coin for 100 Steloj was struck in 2018 for the 150th birthday of René de Saussure.