1820 in Ireland

Events from the year 1820 in Ireland.

Events

30 January – Irish-born Royal Navy captain Edward Bransfield in the Williams is the first person positively to identify Antarctica as a land mass.
12 February – the East Indian and Fanny set sail from Cork with settlers for the Cape Colony.
6 May – failure of Newport's Bank in Waterford.
25 May – failure of Roche's Bank and stoppage of Leslie's Bank in Cork.
3 June – the Roman Catholic Cathedral of St Mary and St Anne in Cork is largely destroyed by arson.
8 July – act for lighting the city and suburbs of Dublin with gas.
20 July – Saint Cronan's Boys' National School opens in Bray, County Wicklow, as the Bray Male School.
December – Lough Allen Canal, giving through navigation between Carrick-on-Shannon and Lough Allen, opens.
The Royal Dublin Society adopts its "Royal" prefix when the new king George IV of the United Kingdom becomes its patron.
Suspension of construction of the Wellington Testimonial, Dublin, in Phoenix Park to the design of Robert Smirke.
First steamship on the Irish Sea crossing from Dublin to Liverpool, the Waterloo, introduced by George Langtry of Belfast.
Frederick Bourne begins to create the village of Ashbourne, County Meath.
Publication of James Hardiman's The History of the Town and County of the Town of Galway, from the earliest period to the present time in Dublin.
Denny Meats are founded.
St. John's Church is built in Ballymore Eustace, County Kildare.

19 February – John Tuigg, third Roman Catholic Bishop of Pittsburgh, Pennsylvania.
31 May – Timothy Burns, Lieutenant Governor of Wisconsin from 1851 to 1853.
3 June – Thomas William Moffett, scholar, educationalist and president of Queen's College Galway.
4 June – John Kean, businessman and politician in Ontario.
2 August – John Tyndall, physicist.
6 October – James Travers, soldier, recipient of the Victoria Cross for gallantry in 1857 at Indore, India.
22 November – Katherine Plunket, botanical artist and longest-lived Irish person ever.
30 December – Mary Anne Sadlier, novelist.
;Full date unknown
:*Thomas Bellew, Galway landowner and politician.
:* John F. Kennedy's great-grandfather was born in the village of Dunganstown in County Wexford.
:*Johnston Drummond, early settler of Western Australia, botanical and zoological collector.
:*Ambrose Madden, recipient of the Victoria Cross for gallantry in 1854 in the Crimea, at Little Inkerman.
:*Patrick Mylott, soldier, recipient of the Victoria Cross for gallantry in 1857 in India.
:*Henry Hamilton O'Hara "Mad O'hara", "The Mad Squire of Craigbilly".
:*Kivas Tully, architect.

29 January – George III of the United Kingdom of Great Britain and Ireland.
5 February – William Drennan, physician, poet, educationalist and co-founder of the Society of United Irishmen.
13 February – Leonard McNally, informant against members of the Society of United Irishmen.
20 March – Eaton Stannard Barrett, poet and author.
6 June – Henry Grattan, member of Irish House of Commons and campaigner for legislative freedom for the Irish Parliament.
Undated – Anthony Daly, a leader of the Whiteboy movement, hanged for attempted murder.