Joseph Louis Anne Avenol ([ʒo.zɛf lwi an av.nɔl]; June 9, 1879 – September 2, 1952) was a French diplomat. He served as the second Secretary General of the League of Nations, from July 3, 1933 to August 31, 1940. He was preceded by Sir Eric Drummond of the United Kingdom, who was general secretary between 1920 and 1933, and he was succeeded by the Irish diplomat Seán Lester, who was general secretary between 1940 and 1946, when the League was dissolved.
Avenol was sent to the League of Nations from the French Treasury Department in 1922 to handle the League's finances. He was under secretary-general in 1933, when Eric Drummond resigned. He became secretary-general because the first secretary-general had been British and there had been a private agreement at Versailles that the next would be French. Avenol was accused of using the League as an extension of the French Foreign Office in its policy of appeasement of Germany and Italy.
Avenol took office shortly after Japan had left the League. Shortly thereafter Germany also left. He worked to prevent action or criticism of those countries in an effort to lure them back to the League. When Italy invaded Ethiopia in 1935, Avenol's main concern was to keep the Italians in the organization, not to protect Ethiopia.
Later Avenol described "a new France, which was to be given a new soul to work in collaboration with Germany and Italy and keep the British out of Europe". He wrote to Marshal Philippe Pétain to affirm his loyalty to the Vichy government.
In the meantime, he had fired most of the League's staff, including all the British employees. On August 31, 1940, Avenol left Geneva and the League of Nations for good. His services were not accepted by the Vichy government, and he was forced to flee back into Switzerland on New Year's Eve 1943 to avoid arrest by the Germans. He died in Switzerland in 1952, aged 73.