John O'Leary (3 May 1933 – 5 October 2015) was an Irish Fianna Fáil politician who served for more than thirty years as Teachta Dála (TD) for the Kerry South constituency.
He was born in Dunrine in the Parish of Kilcummin, Killarney in 1933, and educated at Coolick National School and St. Brendan's College, Killarney. He joined the staff of Kerry County Council in 1952 and worked in Housing, Accounts and Health sections over the next 10 years. In July 1962 he was appointed as Acting town clerk, Killarney Urban District Council and later appointed Staff Officer in the Health and Hospitals section of Kerry County Council. When the new Planning department of the Council was launched O'Leary was put in charge of this until his resignation and election to Dáil Éireann in 1966.
O'Leary was first elected to Dáil Éireann at the December 1966 by-election to succeed Honor Crowley. Honor Crowley had previously succeeded her husband, Frederick Crowley in 1945. He was re-elected at the 1969 general election and was subsequently appointed to the Dáil Select Committee on Procedures and Privileges from 1969–1973. He also represented the government at the 1st World Conference on the Environment in Stockholm in 1972. He was one of five TDs to attend the funerals of the victims of Bloody Sunday in Derry in 1972.
He was re-elected at the head of the poll at the 1973 general election. He was appointed to membership of the Council of Europe from 1973–75 on the nomination of the Fianna Fáil Leader Jack Lynch and from 1975–77 he served as Opposition spokesperson on Physical Planning and the Environment.