| Office: | Judge of the High Court |
| Term Start: | 19 April 2002 |
| Term End: | 9 September 2006 |
| Nominator: | Government of Ireland |
| Appointer: | Mary McAleese |
| Office1: | Judge of the Circuit Court |
| Term Start1: | 3 March 1995 |
| Term End1: | 19 April 2002 |
| Nominator1: | Government of Ireland |
| Appointer1: | Mary Robinson |
| Office2: | Senator |
| Term Start2: | 23 February 1983 |
| Term End2: | 25 April 1987 |
| Term Start3: | 8 October 1981 |
| Term End3: | 13 May 1982 |
| Constituency3: | Nominated by the Taoiseach |
| Office4: | Lord Mayor of Cork |
| Term Start4: | 11 June 1972 |
| Term End4: | 4 June 1973 |
| Predecessor4: | Timothy J. O'Sullivan |
| Successor4: | Patrick Kerrigan |
| Birth Date: | 7 June 1941 |
| Birth Place: | Cork, Ireland |
| Death Place: | Blackrock, Dublin, Ireland |
| Nationality: | Irish |
| Party: | Fine Gael |
| Children: | 5 |
| Relatives: | John Horgan (grandfather) |
| Education: | St Finbarr's College, Farranferris |
Seán Anthony O'Leary (7 June 1941 – 22 December 2006) was an Irish judge, politician and barrister who served as a judge of the High Court from 2002 to 2006, a judge of the Circuit Court from 1995 to 2002, a senator from 1981 to 1982 and 1983 to 1987, and Lord Mayor of Cork from 1972 to 1973.[1]
O'Leary was Lord Mayor of Cork from 1972 to 1973, having been a Fine Gael member of Cork City Council. He was an unsuccessful Fine Gael candidate for Dáil Éireann at the 1965, 1969, 1973 and 1977 general elections for various Cork constituencies. In 1981, he was nominated by the Taoiseach, Garret FitzGerald as a member of the 15th Seanad.[2] He was a political activist one of the group known as the 'National Handlers'. Prior to qualifying as a barrister, he was an accountant. He was nominated again as a senator in 1983, and served in the 17th Seanad from 1983 to 1987. He did not seek re-election in 1987.[2]
He was later appointed a Circuit Court judge and later again elevated to the High Court. He chaired enquiries into the proposed Luas light rail system for Dublin in 1997 and 1999, which were praised for their promptness. While a High Court judge, he served as Chairman of the Residential Institutions Redress Board. He died at his Dublin home on 22 December 2006.[2]
His grandfather John Horgan was a Teachta Dála (TD), as well as a Lord Mayor of Cork from 1941 to 1942.[3] [4]