Seán Brosnan (21 December 1916 – 18 April 1979) was an Irish barrister and Fianna Fáil politician from County Cork. He served for 10 years in the Oireachtas, as a Teachta Dála (TD) and as a Senator.
At the 1969 general election, Brosnan was elected to the 19th Dáil as a TD for Cork North–East. It was his second attempt — he had been defeated in 1965 — and he lost his seat at the 1973 general election. He was then elected to the 13th Seanad Éireann on the Administrative Panel, but he regained his Dáil seat in a by-election in November 1974 after the death of his Fianna Fáil colleague Liam Ahern.
Brosnan was re-elected at the 1977 general election to the 21st Dáil, and also served as a Member of the European Parliament (MEP). MEPs were at that time appointed by national parliaments rather than being elected, and Brosnan was one of a 10-member delegation from the Oireachtas until the first direct elections in 1979.
After his death in 1979, the resulting by-election on 7 November was won for Fine Gael by Myra Barry.