The Memphis massacre of 1866 was a series of violent events that occurred from May 1 to 3, 1866 in Memphis, Tennessee. The racial violence was ignited by political and social racism following the American Civil War, in the early stages of Reconstruction. After a shooting altercation between white policemen and black veterans recently mustered out of the Union Army, mobs of white residents and policemen rampaged through black neighborhoods and the houses of freedmen, attacking and killing black soldiers and civilians and committing many acts of robbery and arson.

Federal troops were sent to quell the violence and peace was restored on the third day. A subsequent report by a joint Congressional Committee detailed the carnage, with blacks suffering most of the injuries and deaths by far: 46 black and 2 white people were killed, 75 black people injured, over 100 black persons robbed, 5 black women raped, and 91 homes, 4 churches and 8 schools (every black church and school) burned in the black community. Modern estimates place property losses at over $100,000, suffered mostly by black people. Many black people fled the city permanently; by 1870, their population had fallen by one quarter compared to 1865.

Public attention following the riots and reports of the atrocities, together with the New Orleans massacre of 1866 in July, strengthened the case made by Radical Republicans in the U.S. Congress that more had to be done to protect freedmen in the Southern United States and grant them full rights as citizens. The events influenced the passage of the Fourteenth Amendment to the United States Constitution, which granted full citizenship to African Americans, as well as the Reconstruction Act, which established military districts and oversight in certain states.Investigation of the riot suggested specific causes related to competition in the working class for housing, work, and social space: Irish immigrants and their descendants competed with freedmen in all these categories. The white planters wanted to drive freedmen out of Memphis and back to plantations, to support cotton cultivation with their labor. The violence was a way to enforce social order after the end of slavery.