The "Mark of the Beast" is a concept from the Christian Bible, specifically found in the Book of Revelation. It is often associated with the number 666 and is believed to signify allegiance to the Antichrist during the end times. Those who receive the mark are said to be unable to buy or sell, indicating a form of control over individuals. This mark is interpreted in various ways, ranging from a literal physical mark to a symbolic representation of loyalty to evil forces. The idea has influenced popular culture, leading to numerous discussions and depictions in literature, movies, and art regarding its implications and meanings.