Christian feast of St. Michael the archangel, celebrated in the Western churches on September 29 and in the Eastern (Eastern Orthodoxy) (Orthodox) Church on November 8. In the Roman Catholic Church (Roman Catholicism), it is the Feast of SS. Michael, Gabriel, and Raphael, archangels; in the Anglican (Anglicanism) Church, its proper name is the Feast of St. Michael and All Angels.

The cult of St. Michael began in the Eastern Church in the 4th century and spread to Western Christianity by the 5th century; the date of May 8 commemorates the dedication of a sanctuary to St. Michael at Monte Gargano in Italy in the 6th century. Because of St. Michael's traditional position as leader of the heavenly armies, veneration of all angels was eventually incorporated into his cult.

During the Middle Ages, Michaelmas was a great religious feast and many popular traditions grew up around the day, which coincided with the harvest in much of western Europe. In England it was the custom to eat a goose on Michaelmas, which was supposed to protect against financial need for the next year. In Ireland, finding a ring hidden in a Michaelmas pie meant that one would soon be married.