1881 in Ireland

• 16 January – the lowest temperature ever recorded in Ireland, −19.1C (−2.4F) at Markree, County Sligo.^[1]
• 3 February – arrest of Michael Davitt.^[2]
• 2 March – Protection of Persons and Property (Ireland) Act 1881, a Coercion Act, is passed.^[2]
• June – the submarine "Fenian Ram" (Holland Boat No. II), designed by Irish-born John Philip Holland and financed by the American Fenian Brotherhood, is first submersion-tested in New York City.
• 22 August – William Ewart Gladstone's Land Law (Ireland) Act 1881, the second of the Irish Land Acts, secures the three "f"s (fair rents, fixity of tenure and freedom of sale),^[3] and gives the courts the authority to reconsider judicial rents every three years and to adjust them in line with shifts in agricultural prices.^[4]
• 13 October – arrest of Charles Stewart Parnell and other leaders.^[2]
• 18 October – No Rent Manifesto.^[2]
• 19 October – Irish National Land League proclaimed as an unlawful association.^[2]

Date unknown

• Sirocco Works, an engineering firm was founded in Belfast by Samuel Cleland Davidson.^[5]
• Kilmacud Monastery established by Carmelite nuns.
• Approximate date – St John Ambulance Ireland establishes its first centre, in Dublin.

• June – Oscar Wilde's Poems published in London.^[6]

• 23 January – William O'Brien, politician and trade unionist (died 1968).
• 10 February – Ken McArthur, winner of the marathon race at the 1912 Summer Olympics for South Africa (died 1960).
• 15 February – Piaras Béaslaí, member of the Irish Republican Brotherhood, member of Dáil Éireann, author, playwright, biographer and translator (died 1965).
• 14 March – Robert Barton, Sinn Féin MP, Cabinet Minister and signatory of Anglo-Irish Treaty 1921 (died 1975).
• 21 March – Seán O'Hegarty, Irish Republican Army member during the Irish War of Independence (died 1963).
• 25 March – Moya Llewelyn Davies, born Mary Elizabeth O'Connor, Republican activist and Gaelic scholar (died 1943).
• 28 March – Martin Sheridan, Olympic gold medallist for the United States (died 1918).
• 10 April – William John Leech, painter (died 1968).
• 24 April – John Joe O'Reilly, Cumann na nGaedheal and Fine Gael TD (died 1967).
• 5 May – Horace de Vere Cole, prankster (died 1936 in France)
• 20 May – Robert Gregory, cricketer, artist and airman (shot down 1918 in Italy).
• 26 July – James Cecil Parke, international rugby player, tennis player, golfer and Olympic medallist (died 1946).
• 21 September – Éamonn Ceannt, nationalist, rebel and Easter Rising leader (executed 1916).
• 13 November
  • Con Collins, Sinn Féin MP (died 1937).
  • John Tudor Gwynn, cricketer (died 1956).
• 8 December – Padraic Colum, poet, novelist and dramatist (died 1972).
• 25 December – John Dill, British Army field marshal (died 1944 in the United States).
• Full date unknown
  • William Conor, artist (died 1968).
  • Seumas O'Kelly, journalist and author (died 1918)

• 30 January – Anna Maria Hall, novelist (born 1800).
• January – Alfred Elmore, painter (born 1815).
• 5 February – Richard Graves MacDonnell, lawyer, judge and colonial governor (born 1814).
• 1 August – Nathaniel Thomas Hone, cricketer (born 1861).
• 9 September – Robert Carew, 2nd Baron Carew, politician (born 1818).
• 10 October – Richard Turner, iron-founder (born 1798).
• 5 November – Robert Mallet, geologist, civil engineer and inventor (born 1810).
• 7 November – John MacHale, Roman Catholic Archbishop of Tuam, Irish Nationalist and writer (born 1791).

• 1881 in Scotland
• 1881 in Wales