The I Threes were a Jamaican reggae singing group made up of three women, that was formed in 1974 to support Bob Marley & The Wailers after Peter Tosh and Bunny Wailer - the original Wailer backing vocalists - left the band.
The three members were Marley's wife Rita Marley, plus Judy Mowatt and Marcia Griffiths. Their name is intended as a spin on the Rastafarian "I and I" concept of the Godhead within each person. (Source: Wikipédia)