William McStay (21 June 1892 – 3 September 1960) was a Scottish international footballer who played as a fullback.
McStay began his senior career when he joined Celtic from Larkhall Thistle in 1912, although he was immediately loaned to Ayr United, spending the following four seasons with the Somerset Park club.
[5] McStay was suspended by Celtic following a wages dispute in the aftermath of their 1923 Scottish Cup Final victory, and he spent the summer in the United States; he played one game with New York Field Club in the American Soccer League.
He made his debut in a 2–1 defeat of Wales at Pittodrie and also played in the match against Ireland two weeks later.
[15] In addition to his siblings, McStay has several family footballing connections: his great-nephews Paul and Willie also played for Celtic in the 1980s and 1990s (Paul also captaining the club and gaining 76 caps for Scotland),[16] their younger brother Raymond also played professionally, their father John was a scout for the club[17] and their cousin Jock McStay was also a professional in the same era.