| Office: | Teachta Dála |
| Term Start: | May 1983 |
| Term End: | 21 June 1986 |
| Constituency: | Donegal South-West |
| Birth Date: | 3 October 1937 |
| Birth Place: | County Donegal, Ireland |
| Death Place: | County Donegal, Ireland |
| Party: | Fianna Fáil |
| Children: | Mary Coughlan |
| Relatives: | Clement Coughlan (brother) |
Cathal Seán Coughlan (3 October 1937 – 21 June 1986) was an Irish Fianna Fáil politician.[1] He was first elected to Dáil Éireann in a 1983 by-election caused by the death of his brother, Clement Coughlan.[2] 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.