The Rastafari movement, or Rasta, is a spiritual movement. It arose in the 1930s in Jamaica, a country with a predominantly Christian culture where 98% of the people were the black descendants of slaves. Most of its adherents worship Haile Selassie I, Emperor of Ethiopia (ruled 1930–1974), as God incarnate, the Second Advent, or the reincarnation of Jesus. Members of the Rastafari movement are known as Rastas, or Rastafari. The movement is sometimes referred to as "Rastafarianism", but this term is considered derogatory and offensive by some Rastas, who, being highly critical of "isms" (which they see as a typical part of "Babylon culture"), dislike being labelled as an "ism" themselves.

The name Rastafari is taken from Ras Tafari, the pre-regnal title of Haile Selassie I, composed of Amharic Ras (literally "Head", an Ethiopian title equivalent to Duke), and Haile Selassie's pre-regnal given name, Tafari. Rastafari are generally distinguished for asserting the doctrine that Haile Selassie I, the former and final Emperor of Ethiopia, is another incarnation of the Christian God, called Jah. Most see Haile Selassie I as Jah or Jah Rastafari, who is the second coming of Jesus Christ onto the Earth, but to others he is simply God's chosen king on earth.