The Greensboro massacre was a deadly confrontation which occurred on November 3, 1979, in Greensboro, North Carolina, US, when members of the Ku Klux Klan and the American Nazi Party (ANP) shot and killed five participants of a "Death to the Klan" march organized by the Communist Workers Party (CWP). The killed included four members of the CWP, who had originally come to Greensboro to support workers' rights activism among mostly black textile industry workers in the area. The Greensboro city police department had an informant within the KKK and ANP group who notified them that the Klan was prepared for armed violence.

The event had been preceded by inflammatory rhetoric from both sides. As the two opposing groups came in contact at the onset of the march, both sides exchanged gunfire. The CWP and supporters had one or more handguns, while members of the KKK and the ANP were shown in a video taking rifles from their cars. In addition to the five deaths, ten demonstrators and a Klansman were wounded.

Two criminal trials of several Klan and ANP members were conducted by state and federal prosecutors. In the first trial, conducted by the state, five were charged with first-degree murder and felony riot. All were acquitted by a jury that concluded that the defendants acted in self-defense. A second, federal criminal civil rights trial in 1984, was brought against nine defendants. The trial resulted in an acquittal of all defendants, when the jury concluded that the men had acted based on political, rather than racial, motivations.

In 1980, surviving protesters filed a separate civil suit, led by the Christic Institute, against 87 defendants, seeking damages of $48 million. Defendants included the city of Greensboro, state of North Carolina, the Justice Department and the FBI. The suit alleged civil rights violations, failure to protect demonstrators, and wrongful death. Eight defendants were found liable for the wrongful death of the one protester who was not a member of the CWP. The city settled with the plaintiffs for $351,000.In 2004, 25 years after the event, a private organization formed the Greensboro Truth and Reconciliation Commission, modeled after commissions in South Africa, Canada and elsewhere with the intention to investigate the events of 1979. The private organization failed to secure authority or local sanction, when the mayor and most of the City Council voted against endorsing the undertaking. The commission lacked both subpoena power to compel testimony, and the ability to invoke perjury for false testimony. When it issued its Final Report, the commission concluded that both sides had engaged in inflammatory rhetoric, but the Klan and ANP members had intended to inflict injury on protesters, and the police department had colluded with the Klan by allowing anticipated violence to take place.

In 2009, the Greensboro City Council passed a resolution expressing regret for the deaths in the march. In 2015 the city unveiled a marker to memorialize the Greensboro Massacre. Three hundred people attended the ceremony.

On August 15, 2017 and on October 6, 2020, the Greensboro City Council formally apologized for the massacre.