William "Billy" Reay (August 21, 1918 - September 23, 2004) was a National Hockey League hockey player and coach. Born in Winnipeg, Manitoba, he played in the NHL for 10 seasons with the Montreal Canadiens and the Detroit Red Wings. In 479 games, he scored 105 goals and 267 points and in 63 playoff games, he scored 13 goals and 29 points. He won two Stanley Cups in 1946 and 1953, both with the Montreal Canadiens. He was an assistant coach for the Toronto Maple Leafs (1957–1959) and a head coach for the Chicago Black Hawks (1963–1977). He has won the most games for a Chicago Black Hawks coach. Although he coached the Black Hawks to three Stanley Cup finals (1965, 1971, and 1973), he was never able to win.