Cathaoirleach (/kəˈhɪərləx/ ⓘ;[2] Irish for chairperson; plural: Cathaoirligh) is the title of the chair (or presiding officer) of Seanad Éireann, the sixty-member upper house of the Oireachtas, the legislature of Ireland.

The current Cathaoirleach is Fianna Fáil Senator Mark Daly, who has held the office since 12 February 2025.

The Cathaoirleach is the sole judge of order, and has a range of powers and functions, namely:[3] The Cathaoirleach is also an ex officio member of the Council of State, which advises the president of Ireland in the exercise of their discretionary powers, and of the Presidential Commission, which performs the powers and functions of the office of president in their absence.

This list includes the panel (since 1938) and political affiliation of each Cathaoirleach, as well as the number of the Seanad and time they spent in the position.

The Cathaoirleach's deputy is the Leas-Chathaoirleach.