Alastair Ian Stewart (born 5 September 1945) is a Scottish singer-songwriter and folk-rock musician who rose to prominence as part of the British folk revival in the 1960s and 1970s. He developed a unique style of combining folk-rock songs with delicately woven tales of characters and events from history.

Stewart is best known for his 1976 hit single "Year of the Cat", the title song from the platinum album of the same name. Though Year of the Cat and its 1978 platinum follow-up Time Passages brought Stewart his biggest worldwide commercial successes, earlier albums such as Past, Present and Future from 1973 are often seen as better examples of his intimate brand of historical folk-rock, a style to which he returned in later albums.

Stewart is a key figure in British music and he appears throughout the musical folklore of the revivalist era. He played at the first-ever Glastonbury Festival in 1970, knew Yoko Ono before she met John Lennon, shared a London flat with a young Paul Simon, and hosted at the Les Cousins folk club in London in the 1960s.