Rosa Luxemburg (Polish: Róża Luksemburg; also Rozalia Luksenburg; 5 March 1871 – 15 January 1919) was a Polish Marxist, philosopher, economist, anti-war activist and revolutionary socialist who became a naturalized German citizen at the age of 28. Successively, she was a member of the Social Democracy of the Kingdom of Poland and Lithuania (SDKPiL), the Social Democratic Party of Germany (SPD), the Independent Social Democratic Party (USPD) and the Communist Party of Germany (KPD).