Karl Liebknecht, German politician (b. 1871)
Karl Paul August Friedrich Liebknecht (German: [ˈliːpknɛçt] (listen); 13 August 1871 – 15 January 1919) was a German socialist politician and theorist, originally of the Social Democratic Party of Germany (SPD) and later a co-founder with Rosa Luxemburg of the Spartacist League and the Communist Party of Germany, which split from the SPD after World War I. He is best known for his opposition to the war in the Reichstag and his role in the Spartacist uprising of January 1919. The uprising was crushed by the SPD government and the Freikorps (paramilitary units formed of World War I veterans), which summarily executed Liebknecht and Luxemburg.

After their deaths, Liebknecht and Luxemburg became martyrs for the socialist cause in Germany and throughout Europe. According to the Federal Office for the Protection of the Constitution, commemoration of Liebknecht and Luxemburg continues to play an important role among the German left, including Die Linke.