Cliff Eisen (born 21 January 1952 in Toronto) is a Canadian musicologist and a Mozart expert. He has been based, since 1997, in the Department of Music at King's College London. He studied at the University of Toronto and at Cornell University, and has taught at the University of Western Ontario and New York University.
Eisen received the Alfred Einstein Award of the American Musicological Society in 1992. His research focuses on the Classical period, particularly Mozart and performance practice. He has written extensively on the issues of authenticity surrounding the works of Leopold Mozart and his son, Wolfgang. Other publications of his deal with Mozart's chamber music, life in Salzburg, biography and his life in contemporary documentation as well as Cole Porter.
Eisen has been an adviser to Robert Levin and Christopher Hogwood for recordings of the complete Mozart piano concertos.
Eisen was reprimanded for misconduct by New York University after sexually harassing Jennifer Miles, a transgender student, in 1997.