Murdock Donald MacInnis (April 4, 1923 – April 20, 2003) was an American composer and associate professor of music at the University of Virginia. MacInnis attended Princeton University, completing his music degree as an undergraduate in 1948 and a masters in 1950. His studies were interrupted by World War II, during which he served with the 13th Armored Division of the United States Army, seeing combat in Germany. While at Princeton, he was musically active, directing the band and managing the Princeton Glee Club. He studied composition and theory with Milton Babbitt, Edward Cone, Joseph Kerman, Bohuslav Martinu, Roger Sessions and Randall Thompson, and conducting with Leonard Bernstein at Tanglewood. MacInnis was elected as an instructor in the faculty of music of the University of Virginia in 1950. He was granted a leave of absence in 1968 to serve as composer in residence with Robert Shaw and the Atlanta Symphony Orchestra. As an instructor, he conducted the University of Virginia Band; later, he was tapped as acting department head in 1955. As a composer, MacInnis employed early electronic music techniques, including computer-synthesized music and tape loops (winning an award from Bowdoin College for his "Variations for Cello and Two-Channel Tape" in 1973). He retired from the University in 1994.