| Office: | Minister of State |
| Suboffice: | Government Chief Whip |
| Subterm: | 1986–1987 |
| Suboffice1: | Defence |
| Subterm1: | 1986–1987 |
| Suboffice2: | Environment |
| Subterm2: | 1983–1987 |
| Suboffice3: | Health |
| Subterm3: | 1982–1983 |
| Suboffice4: | Social Welfare |
| Subterm4: | 1982–1983 |
| Suboffice5: | Government Chief Whip |
| Subterm5: | 1981–1982 |
| Suboffice6: | Defence |
| Subterm6: | 1981–1982 |
| Suboffice7: | Environment |
| Subterm7: | Jun.–Nov. 1981 |
| Office8: | Teachta Dála |
| Term End8: | November 1992 |
| Term Start8: | November 1982 |
| Term Start9: | June 1977 |
| Term End9: | February 1982 |
| Constituency9: | Dublin South-Central |
| Term Start10: | February 1973 |
| Term End10: | June 1977 |
| Constituency10: | Dublin South-East |
| Office11: | Lord Mayor of Dublin |
| Term Start11: | June 1980 |
| Term End11: | June 1981 |
| Predecessor11: | William Cumiskey |
| Successor11: | Alexis FitzGerald |
| Birth Date: | 30 March 1930 |
| Birth Place: | Dublin, Ireland |
| Death Place: | Ranelagh, Dublin, Ireland |
| Nationality: | Irish |
| Party: | Fine Gael |
| Children: | 6 |
| Alma Mater: | Dublin Institute of Technology |
Fergus O'Brien (30 March 1930 – 19 October 2016) was an Irish Fine Gael politician who served as Government Chief Whip and Minister of State at the Department of Defence from 1981 to 1982 and 1986 to 1987 and Lord Mayor of Dublin from 1980 to 1981. He served as a Teachta Dála (TD) from 1973 to 1982 and 1982 to 1992.[1]
O'Brien was born in Dublin in 1930. He was educated at the College of Technology, Bolton Street, before becoming involved in politics. O'Brien was elected to Dáil Éireann on his second attempt at the 1973 general election as a Fine Gael TD for the Dublin South-East constituency.[2] After boundary changes, he was re-elected at the 1977 general election for Dublin South-Central and held the seat at the 1981 general election, but was defeated at the February 1982 general election. He was re-elected for Dublin South-Central at the November 1982 general election, and held the seat until retirement in 1992.
From 1981 to February 1982, O'Brien was Government Chief Whip in Garret FitzGerald's first government. He returned as Chief Whip once again at the end of FitzGerald's second government, serving from 1986 until 1987.
He was Lord Mayor of Dublin from 1980 to 1981.[3]