Lyndon Hermyle LaRouche Jr. was an American political activist who founded the LaRouche movement and its main organization, the National Caucus of Labor Committees (NCLC). He was a prominent conspiracy theorist and perennial presidential candidate. He began in far-left politics in the 1940s and later supported the Civil Rights movement, but in the 1970s he moved to the far-right. His movement is sometimes described as, or likened to, a cult. Convicted of fraud, he served five years in prison from 1989 to 1994.

The LaRouche movement is a political and cultural network promoting the late Lyndon LaRouche and his ideas. It has included many organizations and companies around the world, which campaign, gather information and publish books and periodicals. LaRouche-aligned organizations include the National Caucus of Labor Committees, the Schiller Institute, the Worldwide LaRouche Youth Movement and, formerly, the U.S. Labor Party. The LaRouche movement has been called "cult-like" by The New York Times.