Events from the year 1787 in Ireland.
- 19 August – John Butler, 12th Baron Dunboyne, having resigned as Roman Catholic Bishop of Cork and married a cousin, Maria, contrary to his vow of celibacy, swears oaths of allegiance, abjuration and Supremacy of the monarch as Supreme Governor of the Church of England in Clonmel, the only authenticated apostate in the Catholic hierarchy in Ireland.
- 30 August – the Richardson Baronetcy, of Augher in the County of Tyrone, is created in the Baronetage of Ireland for William Richardson.
- 31 August – the Carden Baronetcy, of Templemore in the County of Tipperary, is created in the Baronetage of Ireland for John Carden, commander of the 30th Regiment of Light Dragoons, which he had helped raise.
- 3 September – the Leslie Baronetcy, of Tarbert in the County of Kerry, is created in the Baronetage of Ireland for Edward Leslie.