Sergey Vladimirovich Girinis (Lithuanian: Sergejus Girinis, Russian: Сергей Владимирович Гиринис, 1882–1961), until 1919 known as Raul Isaakovich Ginzburg (Lithuanian: Raulas Ginsburgas, Russian: Рауль Исаакович Гинцбург), was a Soviet revolutionary, journalist and trade unionist.[1][2][3] He was a leading figure in the labour movement in Vilna (Vilnius) in the 1910s, adhering to a Menshevik-Internationalist line. He later joined the Communist Party of Lithuania. After a prisoner exchange, he was based in Moscow and represented Lithuanian trade unions in the Red International of Labour Unions (Profintern). Girinis was a prolific writer, authoring different works on political theory and history.