William "Billy" J. Simpson (born 12 December 1929 in Belfast) is a former Northern Ireland international footballer.
Simpson signed for Rangers from Linfield for a sum of £11,500 in 1950. He spent nine years (1950–59) at Rangers making 239 appearances and scoring 163 goals. He won three championship medals and a Scottish Cup winners medal with Rangers to add to the two Irish League and two Irish Cups he won with Linfield. He left Ibrox in 1959 and spent the last couple of years of his career with Stirling Albion, Partick Thistle and (then non-league) Oxford United.
Most notably, Billy Simpson scored twice in the "Ne'erday" Old Firm Derby at Ibrox, in a famous 3-1 victory, immortalised in the song 'A Trip to Ibrox'. In recognition of his service to that club, Simpson has been made a member of the Rangers F.C. Hall of Fame.
Simpson made his debut for Northern Ireland in 1951 against Wales, scoring in the process. He represented his country twelve times in total between 1951 and 1958, scoring 5 goals. He was selected in Northern Ireland's squad for the 1958 FIFA World Cup in Sweden but a late injury ensured he did not play at all during the finals.
In April 2015, the feature-length documentary Spirit of '58 was screened as part of the Belfast Film Festival. It featured Billy Simpson prominently alongside the other surviving players (Billy Bingham, Peter McParland, Jimmy McIlroy and Harry Gregg) as it told the story of Northern Ireland's journey throughout the 1950s under the managership of Peter Doherty, culminating in the 1958 World Cup.