While now associated with costumes, trick-or-treating, and scary movies, Halloween wasn’t always a time of fun and games. The holiday had its origins in Samhain, one of the most-sinister festivals on the Celtic calendar. The ancient Celts believed that on November 1 the souls of those who had died returned to visit their homes or to journey to the otherworld. People set fires to frighten away evil spirits, and they sometimes wore masks and other disguises to avoid being recognized by ghosts.
In the 8th century, however, the Roman Catholic Church—perhaps in an effort to end the pagan holiday—moved All Saints’ Day to November 1. The evening before became a holy, or hallowed, eve and thus Halloween. While the day was celebrated by some Christians, many of the Samhain traditions persisted, and Halloween eventually became more commonly known as a secular holiday.