The Hatfields and the McCoys were two families who lived across from each other on the Kentucky/West Virginia border. A bitter feud between the two families lasted for over thirty years, taking the lives of at least 12 men. The famous feud between the Hatfields and the McCoys is often used as a comparison when talking about bitter family feuds, and the fraught emotions of the feud itself are sometimes liked to the Shakespeare's Romeo and Juliet. Like many stories about 19th century America, it can be difficult to sort fact from fiction when examining accounts of the Hatfields and the McCoys.

The feud probably had its roots during the Civil War, when ironically enough both families were on the same side. Both families were farmers, and were relatively well off. They felt that the Civil War threatened their lifestyles, and William Anderson Hatfield and Randolph McCoy both led anti-Union guerilla groups. However, rivalries between to the two families began to be intense during the war, especially after the death of Asa McCoy, who fought on the side of the Union.

In 1873, the Hatfields and the McCoys entered into a bitter dispute over the ownership of a hog. In 19th century America, taking someone else's livestock was viewed as a serious offense, since a single pig could contribute many cuts of meat to the winter larder. A McCoy claimed that a Hatfield had a pig which did not belong to him, and the matter was brought to trial before another Hatfield. Predictably, the final verdict was in favor of the Hatfield, and the feud of the Hatfields and the McCoys began. In 1880, the presiding judge was killed by two McCoy brothers, the first in a string of deaths linked to the feud.

Matters were complicated further in the 1880s when a McCoy daughter fell in love with a Hatfield son, leaving her family to live with the Hatfields. She later returned, followed by her husband, who was kidnapped by the McCoys and later rescued by a group of Hatfields. The feud attracted national attention, even leading to a call out of the militia in an attempt to put a stop to the social unrest and deaths associated with the Hatfields and the McCoys. In 1891, a truce was finally called between the Hatfields and the McCoys, and over 100 years later, in 2000, a reunion featuring both families was held, featuring friendly references to the infamous feud. The term "the Hatfields and the McCoys" is still used popularly in America to refer to two warring families.