Rastafari, sometimes called Rastafarianism, is a religion that developed in Jamaica during the 1930s. It is classified as both a new religious movement and a social movement by scholars of religion. There is no central authority in control of the movement and much diversity exists among practitioners, who are known as Rastafari, Rastafarians, or Rastas.

Rastafari beliefs are based on a specific interpretation of the Bible. Central is a monotheistic belief in a single God, referred to as Jah, who is deemed to partially reside within each individual. Rastas accord key importance to Haile Selassie, the emperor of Ethiopia between 1930 and 1974; many regard him as the Second Coming of Jesus and Jah incarnate, while others see him as a human prophet who fully recognised Jah's presence in every individual. Rastafari is Afrocentric and focuses attention on the African diaspora, which it believes is oppressed within Western society, or "Babylon". Many Rastas call for this diaspora's resettlement in Africa, a continent they consider the Promised Land, or "Zion". Some practitioners extend these views into black supremacism. Rastas refer to their practices as "livity". Communal meetings are known as "groundations", and are typified by music, chanting, discussions, and the smoking of cannabis, the latter regarded as a sacrament with beneficial properties. Rastas emphasise what they regard as living "naturally", adhering to ital dietary requirements, wearing their hair in dreadlocks, and following patriarchal gender roles.

Rastafari originated among impoverished and socially disenfranchised Afro-Jamaican communities in 1930s Jamaica. Its Afrocentric ideology was largely a reaction against Jamaica's then-dominant British colonial culture. It was influenced by both Ethiopianism and the Back-to-Africa movement promoted by black nationalist figures such as Marcus Garvey. The religion developed after several Protestant Christian clergymen, most notably Leonard Howell, proclaimed that Haile Selassie's crowning as Emperor of Ethiopia in 1930 fulfilled a Biblical prophecy. By the 1950s, Rastafari's countercultural stance had brought the movement into conflict with wider Jamaican society, including violent clashes with law enforcement. In the 1960s and 1970s, it gained increased respectability within Jamaica and greater visibility abroad through the popularity of Rastafari-inspired reggae musicians, most notably Bob Marley. Enthusiasm for Rastafari declined in the 1980s, following the deaths of Haile Selassie and Marley, but the movement survived and has a presence in many parts of the world.

The Rastafari movement is decentralised and organised on a largely sectarian basis. There are several denominations, or "Mansions of Rastafari", the most prominent of which are the Nyahbinghi, Bobo Ashanti, and the Twelve Tribes of Israel, each offering a different interpretation of Rastafari belief. There are an estimated 700,000 to 1,000,000 Rastafari across the world. The largest population is in Jamaica, although small communities can be found in most of the world's major population centres. Most Rastafari are of black African descent, and some groups accept only black members.

Haile Selassie I (Ge'ez: ቀዳማዊ ኀይለ ሥላሴ, romanized: Qädamawi Häylä Səllasé, Amharic pronunciation: [ˈhaɪlə sɨlˈlase] (listen); born Tafari Makonnen; 23 July 1892 – 27 August 1975) was Emperor of Ethiopia from 1930 to 1974. He raised to power as Regent Plenipotentiary of Ethiopia for Empress Zewditu from 1916. Haile Selassie is widely considered a defining figure in modern Ethiopian history, and the key figure of Rastafari, a religious movement in Jamaica which emerged shortly after he became emperor in the 1930s. He was a member of the Solomonic dynasty which claims to trace lineage to Emperor Menelik I, believed to be the son of King Solomon and Makeda the Queen of Sheba.

Haile Selassie attempted to modernize the country through a series of political and social reforms, including the introduction of 1931 constitution, its first written constitution, and the abolition of slavery. He led the failed efforts to defend Ethiopia during the Second Italo-Ethiopian War and spent most of the period of Italian occupation exiled in England. In 1940, he traveled to Sudan in order to assist in coordinating the anti-fascist struggle in Ethiopia, and returned to his home country in 1941 after the East African campaign. He dissolved the Federation of Ethiopia and Eritrea, which was established by the UN General Assembly in 1950, and annexed Eritrea into Ethiopia as one of its provinces, while fighting to prevent secession.Haile Selassie's internationalist views led to Ethiopia becoming a charter member of the United Nations. In 1963, he presided over the formation of the Organisation of African Unity, the precursor of the African Union, and served as its first chairman. In 1974, he was overthrown in a military coup by a Marxist–Leninist junta, the Derg. Haile Selassie was assassinated on 27 August 1975.Among some members of the Rastafari movement, Haile Selassie is referred to as the returned messiah of the Bible, God incarnate. This distinction notwithstanding, he was a Christian and adhered to the tenets and liturgy of the Ethiopian Orthodox Church. The Rastafari movement was founded in Jamaica sometime around 1930 and its followers are estimated at between 700,000 and one million as of 2012.He has been criticized by some historians for his suppression of rebellions among the landed aristocracy (the mesafint), which consistently opposed his reforms; some critics have also criticized Ethiopia's failure to modernize rapidly enough. During his rule the Harari people were persecuted and many left the Harari Region. His regime was also criticized by human rights groups, such as Human Rights Watch, as autocratic and illiberal. Although some sources state that late during his regime the Oromo language was banned from education, public speaking and use in administration there was never an official law or government policy that criminalized any language. The Haile Selassie government relocated numerous Amharas into southern Ethiopia where they served in government administration, courts, church. Following the death of Hachalu Hundessa in June 2020, the Statue of Haile Selassie in Cannizaro Park, London was destroyed by Oromo protesters, and his father's equestrian monument in Harar was removed.