Levie Jacob "Louis" Fles (19 October 1872 – 24 May 1940) was a Dutch businessman, activist and author. He is best known for writing and broadcasting against Zionism, Nazism, and organized religion. A self-described freethinker, Fles was a vocal supporter of Humanism and Jewish assimilation. His relationship with the Dutch Social Democratic Workers' Party was more problematic. While he generally supported the ideals of socialism, he wrote extensively about his disagreements with the party as well. After a life filled with personal tragedy and devotion to political and social activism, Fles committed suicide in May 1940, only a few weeks after the German occupation of the Netherlands.