Ivan B. "Ivy" Williamson (February 4, 1911 – February 19, 1969) was a player and coach of American football and basketball, and a college athletics administrator. He played college football and basketball at the University of Michigan from 1930 to 1932 and was captain of the national champion 1932 Michigan football team. He was an assistant football coach at Yale University (1934–1941, 1945–1946), the head football coach at Lafayette College (1947–1948) and the University of Wisconsin–Madison (1949–1955). He served as the athletic director at Wisconsin from 1955 to 1969.