William Barbour Agnew (30 December 1880 – 19 August 1936) was a Scottish footballer who played for local club Kilmarnock and Falkirk as well as English clubs Newcastle United, Middlesbrough and Sunderland. Agnew, a defender born in Kilmarnock, was also capped by the Scotland national team, making three appearances between 1907 and 1908. He coached at Third Lanark after his playing career.