William McKay (24 August 1906 – June 1977) was a Scottish footballer who played for Bolton Wanderers and Manchester United in the 1930s.
He helped Manchester United to win promotion out of the Football League Second Division in 1935–36 (as champions) and 1937–38.
He helped United to avoid relegation from the Second Division at the tail end of the 1933–34 season and rise up the table to fifth position in 1934–35.
McKay's career was disrupted by the Second World War, which put an end to the Football League in the first half of the 1940s, though he did turn out for Manchester United in their wartime games.
[1] He was transferred to Cheshire County League club Stalybridge Celtic when football resumed in 1946, his 40-year-old body presumably not fit for action at Old Trafford.