Ernst Christian Einar Ludvig Detlev, Graf zu Reventlow (18 August 1869 – 21 November 1943) was a German naval officer, journalist and Nazi politician.

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] (19 September 1873 - 15 April 1937), forced him to resign his commission.

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 on 25 June 1915.

At first, Reventlow denounced the “delusion of the so-called National Bolsheviks that Communism could turn towards nationalism,”[2] but when Radek seized the occasion of the Ruhr occupation to deliver his Schlageter Oration before the Enlarged Executive Committee of the Comintern in 1923, Reventlow responded with sympathetic articles in Der Reichswart that were subsequently re-printed in the communist central organ Rote Fahne.

Later, he was to write approvingly of the Communist Party of Germany’s domestic policies in the Deutsches Tageblatt and to demand fifty-percent managerial control of any enterprise by the workers.

Reventlow supported a theory first proposed by Lesley Fry (pen-name of Paquita de Shishmareff ) (1882-1970), who in her book Waters Flowing Eastward (Paris: Éditions R.I.S.S., 1931)[5] claimed that the Protocols of the Elders of Zion were the master plan of a conspiracy according to which a group led by "cultural Zionist" Asher Ginzberg plotted world domination.

After Philip Graves provided evidence in The Times that the Protocols were plagiarised forgery, Reventlow published his support for Fry's theory of Ginzberg's authorship in the periodical La Vieille France.