Wilhelm Franz Canaris (1 January 1887 – 9 April 1945) was a German admiral and chief of the Abwehr, the German military intelligence service, from 1935 to 1944. At some point, he became a member of the German resistance, sabotaging Germany's foreign policy and war effort, providing the Allies with information, and providing important support for the German resistance. This has been argued to have been an important cause of Germany losing the war.
The assassination of Reinhard Heydrich on 4 June 1942 has been argued to be related to Heydrich becoming suspicious of Canaris.
At the insistence of Himmler, Hitler dismissed Canaris and abolished the Abwehr in February 1944. Canaris was suspected of involvement in the 20 July plot. Eventually, Canaris, personal diary was discovered, implicating him in the conspiracy. He was executed for high treason shortly before the end of the war.