Events from the year 1815 in Ireland.

• March 28 – laying of the foundation stone of the Metropolitan Chapel (later known as the Catholic Pro-Cathedral), Marlborough Street, Dublin.
• March – poet William Drennan's Fugitive pieces in verse and prose published in Belfast.
• June 4 – lighthouse on Tuskar Rock first illuminated.
• July 6 – Charles Bianconi runs his first car (i.e. horse-drawn carriage) for conveyance of passengers, from Clonmel to Cahir.
• The river paddle steamer City of Cork is launched at Passage West, the first steamboat built in Ireland.^[1]
• The Religious Sisters of Charity are founded by Mary Aikenhead in Dublin.
• The Dublin Society purchases Leinster House, home of the Duke of Leinster, and founds a natural history museum there.^[2]
• Tenter House erected in Cork Street, Dublin, financed by Thomas Pleasants.^[2]
• St. Brendan's Hospital officially opened as the Richmond Lunatic Asylum, a national institution.

• March – William Wilde, surgeon, author and father of Oscar Wilde (died 1876).
• 11 June – Hans Crocker, lawyer and Wisconsin politician (died 1889).
• 24 July – Arnaud-Michel d'Abbadie, geographer (died 1893).
• 24 July – John Thomas Ball, lawyer, politician and Lord Chancellor of Ireland, 1875–1881 (died 1898).
• August – Edmond Burke Roche, 1st Baron Fermoy, politician (died 1874).
• 3 November – John Mitchel, nationalist activist, solicitor and journalist (died 1875).
• 31 December – Chartres Brew, Gold commissioner, Chief Constable and judge in the Colony of British Columbia (died 1870).
• Full date unknown – Alfred Elmore, painter (died 1881).

• 31 December – Thomas Burke, artist (born 1749).
• Ellen Hutchins, botanist (born 1785).

• 1815 in Scotland
• 1815 in Wales