Halloween, or Hallowe'en (; a contraction of All Hallows’ Evening), also known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in a number of countries on 31 October, the eve of the Western Christian feast of All Hallows' Day. It begins the three-day observance of Allhallowtide, the time in the liturgical year dedicated to remembering the dead, including saints (hallows), martyrs, and all the faithful departed.

Halloween is an American horror franchise that consists of ten films, novels, comic books, merchandise, and a video game. The franchise predominately focuses on the fictional character of Michael Myers who was committed to a sanitarium as a child for the murder of his older sister, Judith Myers. Fifteen years later, he escapes to stalk and kill the people of Haddonfield, Illinois while being chased by his former psychiatrist Dr. Sam Loomis. Michael's killings occur on the holiday of Halloween, on which all of the films primarily take place. The films collectively grossed over $366 million at the box-office worldwide. The original Halloween, released in 1978, was written by John Carpenter and Debra Hill, and directed by Carpenter. The sequels have had various writers and directors attached to them. Michael Myers is the antagonist in all of the films except Halloween III: Season of the Witch, the story of which has no direct connection to any other film in the series. Carpenter, who had a hand in writing the first sequel, has not had any direct involvement with the rest of the films. The film series is ranked fourth at the United States box office—in adjusted 2008 dollars—when compared to other American horror franchises. The first Halloween film is credited with beginning a long line of slasher films inspired by Alfred Hitchcock's Psycho. The franchise began when the first novel appeared less than a year after the release of the first film, and seven sequels have since followed. In 2007, director Rob Zombie produced a  remake of the 1978 film. A direct sequel to the 2007 remake was released two years later.