Robert Grimm (16 April 1881 – 8 March 1958) was the leading Swiss Socialist politician during the first half of the 20th century.
As a leading member of the Social Democratic Party of Switzerland he opposed the First World War. Grimm was the main organiser of the Zimmerwald Movement and the chairman of the International Socialist Commission in Berne 1915 – 1917. After the Grimm–Hoffmann Affair he had to resign from this function.