William "Billy" Halligan (18 February 1886 – 1950) was an Irish professional association football player, who played as a centre forward.
Born in Athlone, he started his career in his homeland before moving to England and playing for seven different Football League clubs.
At the end of his career, he also played for two non-league teams.
While playing for Nelson, he scored the club's first ever goal in the Football League, in a 1–2 loss to Wigan Borough on 27 August 1921.
Halligan won two caps for the Ireland national team and scored one goal for his country, in a 1–2 defeat by Wales on 28 January 1911.
His second appearance for Ireland came on 10 February 1912, in the 1–6 loss to England.