William Sayer (22 Jun 1934 – 16 Aug 1989), also known by the nickname of 'Sos', was an English professional rugby league footballer who played in the 1950s, 1960s and 1970s. He played at representative level for Great Britain, and at club level for Wigan Highfield, Wigan (Heritage № 561) and St. Helens (Heritage № 832), as a hooker, i.e. number 9, during the era of contested scrums.