Seán Daniel Treacy was an Irish Labour Party politician who served as Ceann Comhairle of Dáil Éireann from 1973 to 1977 and 1987 to 1997. He served as a Teachta Dála (TD) for the Tipperary South constituency from 1961 to 1997. He also served as a Member of the European Parliament (MEP) for the Munster constituency from 1981 to 1984.

The Ceann Comhairle is the chairperson of Dáil Éireann, the lower house of the Oireachtas (parliament) of Ireland. The person who holds the position is elected by members of the Dáil from among their number in the first session after each general election. The Ceann Comhairle since 10 March 2016 has been Seán Ó Fearghaíl, Fianna Fáil TD. The Leas-Cheann Comhairle since 23 July 2020 has been Catherine Connolly, Independent TD.