Jules-Frédéric Humbert-Droz (23 September 1891, La Chaux-de-Fonds – 16 October 1971) was a Swiss pastor, journalist, socialist and communist. A founding member of the Communist Party of Switzerland, he held high Comintern office through the 1920s and also acted as Comintern emissary to several west European countries. He was involved in the Right Opposition in 1928. He rejoined the Swiss Socialist Party in the 1940s and served as its secretary from 1946 to 1965. He was born in a working-class family of watchmakers with socialist beliefs. His grandfather was a member of the International Workingsmen's Association. Humbert joined the Social Democratic Party of Switzerland (Swiss Socialist Party) in 1911, at the age of 20. After studying Protestant theology in Neuchâtel, Paris and Berlin, he wrote a thesis about Socialism and christianism. He became a pastor in 1914 and started writing in the socialist daily newspaper La Sentinelle soon after. He married Eugénie (Jenny) Perret in 1916, who would accompany him throughout his political life; she became known as Jenny Humbert-Droz. Humbert-Droz opposed the First World War and refused to serve in the Swiss Army, for which he was imprisoned. He received another jail sentence for his participation the 1918 Swiss general strike. He supported the Bolshevik Revolution and travelled with Walther Bringolf to Russia to represent the left wing of the Social Democratic Party of Switzerland. There, both of them joined the Provisional International Bureau of the Kultintern. In 1921, at the Third International Congress of the Comintern, Humbert-Droz was elected secretary of the Communist International, on the proposal of Vladimir Lenin himself. Humbert-Droz became after 1920 an outstanding leader in the international communist movement and travelled all around the world to organize the national sections of the Comitern. He exerted some control over the French Communist Party and called himself the eye of Moscow in Paris. He eventually became the first director of the Latin Secretariat of the Comintern.