Alastair MacLennan (born 1943 in Blair Atholl, Perthshire, Scotland) is one of Britain’s major practitioners of live art. Since 1975, he has been based in Belfast, Northern Ireland. He was a founder member of Belfast’s Art and Research Exchange. He is a member of the performance art collective Black Market International (BMI).

He studied at the Duncan of Jordanstone College of Art and Design of the University of Dundee in 1960-65. 1966-68 he received his Master of Fine Arts from the School of the Art Institute of Chicago, Chicago. He is Emeritus Professor in Fine Art, University of Ulster in Belfast, Honorary Fellow of the Dartington College of Arts, Devon, and Honorary Associate of the National Review of Live Art, Glasgow.

MacLennan’s live work is prevailingly long durational. During the 1970s and 1980s he presented long durational performances in Britain and America, of up to 144 hours. His work looks into political, social, religious, ethical and aesthetical questions.

For his performances and installations, he uses the term “Actuations”