Carroll, Patrick Joseph (1903–75), Garda commissioner, was born 15 September 1903 in Ballyrider, Stradbally, Co. Laois, third among six children of Michael Carroll (d. c.1920) and Julia Carroll (née Buggy) (d. c.1939), farmers. Educated at the CBS, Athy, Co. Kildare, he was active in the IRA during the war of independence (1919–21). Commissioned as a captain in the National Army in 1922, he served as a military policeman at Abbeyleix during the civil war and became assistant battalion adjutant. In June 1923 he joined the Garda Siochána but never received any basic training, working from the outset in the commandant's office. Taking first place in the promotion examinations, he was elevated to the rank of sergeant (October 1923), and after a short time in Cork was promoted to superintendent. Moving to Waterford as district officer, he was transferred back to Dublin as a training officer (1925–34) of Garda recruits. He studied law at the King's Inns (1928–32) and was called to the bar in Michaelmas term 1932, although he never practised.
In collaboration with Michael Horgan he adapted the Royal Irish Constabulary Guide in 1934 for use by the Garda Siochána, and he edited several editions of the resulting Police Guide (1937, 1954, 1967). In 1936 he was appointed acting chief superintendent in charge of the crime division. Assigned to the traffic branch in 1937, he became the youngest chief superintendent on the force in August 1939 and took charge of the special branch, with overall responsibility for political crime and the security of the state. During the second world war he worked closely with military intelligence, investigating the activities of suspected spies, and in 1948 he warned the new minister for external affairs, Seán MacBride (qv), that the special branch had received information of a plot to assassinate him.
After the war he served in the old Dublin/Wicklow division before moving to the new Dublin metropolitan area. Appointed assistant commissioner in January 1962 and deputy commissioner in November 1962, he was appointed commissioner on 5 March 1967 on the retirement of William P. Quinn (1900–78) and served until 14 September 1968. The last police commissioner before the outbreak of the Northern Ireland troubles, he was faced with rising discontent and dissatisfaction over pay and conditions in the force. Closely identified with the Garda representative bodies, he was more public than previous commissioners and was the first to address the rank-and-file elected assemblies. On his retirement he became a director of the Chubb Lock & Safe Co. and the Chubb Alarms Co.
President of the Irish Amateur Boxing Association (1939–75), he was also a member (1947–75), secretary (1958), treasurer (1946–58), and president (1972–5) of the Olympic Council of Ireland, and president of the Garda Golfing Society. Patrick Joseph Carroll lived at 15 Cowper Drive, Rathmines, Dublin. He died 6 December 1975, leaving estate valued at £22,515.
He married (23 February 1927) Agnes (d. 1972) daughter of Joseph Caulfield, pig buyer, and Julia Caulfield (née Brophy) of Glen House, The Glen, Waterford; they had two sons and two daughters. Their younger daughter, Mella Carroll (6 March 1934–15 January 2006), was called to the bar in 1957 and became the second woman to become a senior counsel when she took silk in 1976, the first woman to be chair of the bar council, and the first woman appointed as a judge of the high court (1980).