Saul David Alinsky (January 30, 1909 – June 12, 1972) was an American community organizer and writer. He is generally considered to be the founder of modern community organizing and has been compared in Playboy Magazine to Thomas Paine as "one of the great American leaders of the nonsocialist left."

In the course of nearly four decades of organizing the poor for radical social action, Alinsky made many enemies, but he has received praise from an array of public figures. His organizing skills were focused on improving the living conditions of poor communities across North America. In the 1950s, he began turning his attention to improving conditions of the African-American ghettos, beginning with Chicagos and later traveling to other ghettos in California, Michigan, New York City, and a dozen other "trouble spots."

His ideas were later adapted by some US college students and other young organizers in the late 1960s and formed part of their strategies for organizing on campus and beyond. Time magazine once wrote that "American democracy is being altered by Alinskys ideas," and conservative author William F. Buckley said he was "very close to being an organizational genius."