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 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.
He was re-elected for Dublin South-Central at the November 1982 general election, and held the seat until retirement in 1992.
He returned as Chief Whip once again at the end of FitzGerald's second government, serving from 1986 until 1987.