The Leader of the Opposition (Irish: Ceannaire an Fhreasúra) in Ireland is a de facto term sometimes used to describe the politician who leads the largest party in the parliamentary opposition in Dáil Éireann, the house of representatives of the Oireachtas (the Irish parliament).

Opposition leaders leading a political party with five members or more have full speaking rights under Dáil standing orders; smaller parties and independent politicians are allowed to speak less often.

Historically the two largest parties have nearly always been Fianna Fáil and Fine Gael, and so the position of Leader of the Opposition has alternated between them.

However, since Labour and Fine Gael entered a coalition government, the third largest party, Fianna Fáil, led the opposition in the 31st Dáil.

The Leader of the Opposition as of 2024[update] is Mary Lou McDonald of Sinn Féin, following the formation of a government of Fianna Fáil, Fine Gael and the Green Party on 27 June 2020.