The Greenwich Village townhouse explosion occurred on March 6, 1970, in New York City, United States. Members of the Weather Underground (Weathermen), an American leftist militant group, were making bombs in the basement of 18 West 11th Street in the Greenwich Village neighborhood, when one of them exploded. The resulting series of three blasts completely destroyed the four-story townhouse and severely damaged those adjacent to it, including the then home of actor Dustin Hoffman and theater critic Mel Gussow. Three Weathermen—Ted Gold, Diana Oughton and Terry Robbins—were killed in the blast, while two survivors, Kathy Boudin and Cathy Wilkerson, were helped out of the wreckage and subsequently fled.

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.