Cathal Seán Coughlan (3 October 1937 – 21 June 1986) was an Irish Fianna Fáil politician. He was first elected to Dáil Éireann in a 1983 by-election caused by the death of his brother, Clement Coughlan. His tenure as a Teachta Dála (TD) for Donegal South-West was short as he died suddenly in June 1986. No by-election was held to fill the vacancy, but his daughter, Mary Coughlan, was elected for the constituency at the 1987 general election.