Ernst Christian Einar Ludvig Detlev, Graf zu Reventlow (18 August 1869 – 21 November 1943) was a German naval officer, journalist and Nazi politician.
Ernst Christian Einar Ludvig Detlev, Graf (Count) zu Reventlow was born at Husum, Schleswig-Holstein, the son of Ludvig Christian Detlev Frederik, Graf zu Reventlow (January 6, 1824 - June 14, 1893), a Danish nobleman, and Emilie Julie Anna Louise Rantzau (April 19, 1834 - November 19, 1905). His younger sister was Fanny zu Reventlow (1871-1918), the "Bohemian Countess" of Schwabing. Reventlow embarked upon a career in the German Imperial Navy, reaching the rank of lieutenant commander, before his marriage to a Frenchwoman, Marie-Gabrielle-Blanche d'Allemont [de Broutillot] (September 19, 1873 - April 15, 1937), forced him to resign his commission. Ernst and Blanche were married on March 14, 1895 in Altona, Hamburg, Schleswig-Holstein, Germany. Ernst became a free-lance writer on naval issues, and later general politics.
During World War I, as an editorial writer on the Deutsche Tageszeitung, he advocated extreme ruthlessness, particularly in submarine warfare. He accused United States Ambassador Gerard of being a British spy, but assailed Zimmermann for the plot to form an alliance between Mexico and Japan against the United States. He furiously attacked Germany's leaders for yielding to the United States' demands for respect of its rights after the sinking of the Lusitania, and the Tageszeitung was suspended 25 June 1915. For an attack on Bethmann-Hollweg, accusing him of misleading von Hindenburg, he was sued for slander in 1916.