William Charles Ayers is an American retired professor and former militant organizer. In 1969, Ayers co-founded the far-left militant organization the Weather Underground, a revolutionary group that sought to overthrow what they viewed as American imperialism. During the 1960s and 1970s, the Weather Underground conducted a campaign of bombing public buildings in opposition to U.S. involvement in the Vietnam War. The bombings caused no fatalities, except for three members killed when one of the group's devices accidentally exploded. The FBI described the Weather Underground as a domestic terrorist group. Ayers was hunted as a fugitive for several years, until charges were dropped due to illegal actions by the FBI agents pursuing him and others.

The Weather Underground was a far-left Marxist militant organization first active in 1969, founded on the Ann Arbor campus of the University of Michigan. Originally known as the Weathermen, the group was organized as a faction of Students for a Democratic Society (SDS) national leadership. Officially known as the Weather Underground Organization (WUO) beginning in 1970, the group's express political goal was to create a revolutionary party to overthrow the United States government, which WUO believed to be imperialist.