Wilhelm Canaris, in full Wilhelm Franz Canaris, (born January 1, 1887, Aplerbeck, Westphalia, Germany—died April 9, 1945, Flossenbürg concentration camp, Bavaria), German admiral, head of military intelligence (Abwehr) under the Nazi regime and a key participant in the resistance of military officers to Adolf Hitler.

Having served in the navy during World War I, Canaris was a member of the military tribunal that sentenced the murderers of the German communist theoretician Rosa Luxemburg, and then he allegedly helped one of the condemned officers to escape.

Appointed head of the Abwehr (January 1935), he organized German aid to General Francisco Franco during the Spanish Civil War. Believing that the Nazi regime would ultimately destroy traditional conservative values and that its foreign ambitions were dangerous to Germany, he enlisted some of the anti-Hitler conspirators into the Abwehr and shielded their activities. He was transferred to the economic staff of the armed forces (February 1944) after an investigation of the Abwehr by the Schutzstaffel (SS); he remained there until after the abortive assassination attempt against Hitler (July 20, 1944), when he was arrested and executed.