William P. Quinn (5 March 1900 – 10 January 1978) was born in Inniskeen, County Monaghan, Ireland.
He joined the Garda Síochána in December 1922 and was the first recruit to rise through the ranks to the office of Commissioner.
He joined the Ulster Bank in September 1916, leaving in 1918 to become a volunteer in the Irish Republican Army (IRA).
He served as clerk to the Chief Superintendent, Waterford Division, and on the first of September 1925, was promoted to the rank of Inspector.
On the first of June 1934, he was promoted to Chief Superintendent and took charge of the Tipperary Division, with its headquarters in Thurles.