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. 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.