Athlone, County Westmeath born centre forward Billy Halligan began his football career with Old St Mary’s of Dublin in 1905 and joined Irish amateur club Cliftonville in 1906, where he represented Leinster, signing for Belfast Celtic in July 1907 and joining Distillery in 1908. He came to the notice of English clubs when he was selected for the Irish League against the Scottish League in February 1909 and became one of several Irish players to be signed by Frank Scott-Walford, the Manager of Leeds City in May 1909. Halligan made his Football League debut in their opening fixture that August against Lincoln City at Elland Road and scored a brace as City stormed to a 5-0 win. With City in financial troubles they could not refuse the offer of £400 that Second Division Derby County laid before them in February 1910 after he had scored 11 goals in just 25 appearances. In January 1911 he was capped for Ireland scoring in a 2-1 defeat by England at Windsor Park, Belfast.
However his career at The Baseball Ground never really took off and after 8 goals in 22 appearances he joined Wolverhampton Wanderers for £450 in June 1911. While at Wolves he won when he was selected to play in the 1-6 defeat by England at Dalymount Park, Dublin in February 1912. He was Wolves’ top scorer in both his seasons at Molineux, with an impressive 24 goals in his debut campaign including hat-tricks in an 8-0 thrashing of Hull City in November 1911, in a 5-0 win over Barnsley in March 1912 and in a 10-0 FA Cup mauling of Southern League Watford in January 1912. After 41 goals in 73 appearances for Wolves, they accepted a bid of £600 from fellow Second Division club Hull City in May 1913, for whom he played the final two seasons before the onset of the First World War forced the abandonment of peacetime football.
He bit the hand that used to feed him scoring 4 goals in a 7-1 thrashing of Wolves in December 1913, and was second top scorer at the club, both seasons to Sammy Stevens, as Hull City recorded two 7th placed finishes. During the War he guested for Manchester United, Rochdale, Stockport County and Chesterfield and at its end he played in the two unofficial Victory Internationals, both against Scotland. In the first, played at Hampden Park on 22nd March 1919, he scored the Irish goal in their 2-1 defeat, after Scotland had to play the first twenty minutes with nine men as two players failed to turn up. The second game, played in Belfast on 19th April 1919 resulted in a goalless draw.
On the resumption of peacetime football Halligan signed for First Division Preston North End in July 1919, finally making it to the top flight. However, by then age had caught up with him, and he found the net just twice in 16 appearances for The Lilywhites before signing for Oldham Athletic on a free transfer in January 1920. He scored twice on his Oldham debut in a defeat at Arsenal at the start of February, but broke his ankle when playing in the home game against Bradford Park Avenue on Christmas Day 1920, and joined Nelson once recovered in August 1921 after 9 goals in 28 appearances. 1021-22 proved his final season of League football, scoring 6 goals in 20 appearances for The Admirals, joining non league Boston Town in 1922 and finishing his career by joining Wisbech Town in 1923, where he played until 1925 before finally retiring at the age of 39.