The Honourable Katherine Plunket (22 November 1820 – 14 October 1932) (born as Catherine Plunket) was an Irish aristocrat from Ballymascanlan, County Louth, a prolific botanical illustrator and the oldest born native person from Ireland (oldest person in Irish history), at 111 years and 327 days.
Plunket was born at Kilsaran, near Castlebellingham in County Louth. The eldest of six children, one of whom died in infancy, she was a granddaughter of William Plunket, 1st Baron Plunket, Lord Chancellor of Ireland. Her father Thomas Plunket, 2nd Baron Plunket (1792–1866), was a junior Church of Ireland clergyman when she was born and later became the Bishop of Tuam, Killala and Achonry. Her mother Louise Jane Foster (married in 1819) was the daughter of John William Foster of Fanevalley, County Louth, Member of Parliament for Dunleer, and was related to the Earl of Clermont. Her first and second cousins included three titled members of the Irish aristocracy. She was baptised Anglican in Kilsaran Church on 13 December 1820 as Catherine Plunket, though she spelled her name with a K for her entire life.
She inherited from her mother one of the family's ancestral homes, Ballymascanlon House near Dundalk, and oversaw the upkeep of the home and gardens until she contracted bronchitis at the age of 102 (her only serious health problem). The house is now a hotel. Plunket was the oldest person ever born in Ireland, and the second oldest person from Ireland, as fellow Irish woman supercentenarian Kathleen Snavely was born in the United States.
With her younger sister Gertrude (1841–1924), Plunket traveled widely and visited almost every capital in Europe. With her sister Frederica she made many sketches of flowers in France, Italy, Spain and Germany, and Ireland. These were bound in a volume which was presented in 1903 to the Royal College of Science, and was later transferred to the Museum of Science and Art in the National Museum of Ireland. In 1970 it was part of the collections which were transferred to the Irish National Botanic Gardens at Glasnevin.
Although it was not known at the time, Plunket became the oldest recognised person in the world at 8:00 a.m. on 4 December 1928, after the death of Delina Filkins, at the age of 108 years and 12 days, spanning a little over three years. As well as being the longest-lived Irish person, Plunket lived longer than anyone who died in Ireland or Britain, and at 109 received a telegram from King George V, holding the longevity record title for 38 years, until 1970, when Ada Roe lived to be 12 days older. She was also the last living person who had met the author Sir Walter Scott (1771–1832), when he stayed at her grandfather's house in Bray while she was visiting. She was included in the first ever Guinness World Records (published in 1955), and is the only alleged supercentenarian listed then to stand the burden of scrutiny in the years since. She attributed her longevity to the unrustled carefree aspect of her life. She died on 14 October 1932, a month shy of her 112th birthday and her obituary was published in numerous Irish media publications, and in England in The London Times, a telegram of condolence was sent to her relatives by King George V.
- A.R. Thatcher. "Katherine Plunket: A Well Documented Super-Centenarian in 1930". The Max Planck Institute for Demographic Research. Retrieved 2007-11-22.
- "Art Collections In The National Herbarium". Irish National Botanic Gardens. Retrieved 2007-11-22.
- "Biography of Centenarian Katherine Plunket". trivia-library.com. Retrieved 2007-11-22.
- Burke's Peerage 1970, Plunket also Massereene and Ferrard
- "History of Best Western Ballymascanlon House Hotel". Ballymascanlon House Hotel. Retrieved 2007-11-22.
- A.R. Thatcher. "Annex A: Katherine Plunket and her family". The Max Planck Institute for Demographic Research. Retrieved 2007-11-22.
- The sources are inconsistent on these points. The "Art Collections In The National Herbarium" lists Katherine and Frederica as the artists, but notes Frederica as the donor of the paintings in 1903, although Thatcher's article lists Frederica as having died in 1886.
- A.R. Thatcher. "Extract from "The Spectator", 27 December 1930". The Max Planck Institute for Demographic Research. Retrieved 2007-11-22.
- According to Thatcher (op cit), her case was investigated by Julia Hynes of the Cambridge Group for the History of Population and Social Structure.