Marguerite Gardiner, Countess of Blessington was an Irish novelist.
Born Margaret Power near Clonmel in County Tipperary, Ireland, she was a daughter of Edmund Power, a small landowner. Her childhood was made unhappy by her father's character and poverty, and her early womanhood wretched by her compulsory marriage at the age of fifteen to a Captain Maurice St. Leger Farmer, an English officer whose drunken habits finally brought him as a debtor to the King's Bench Prison, where he died in October 1817.
Marguerite had left him some time before, moving to Hampshire to live with the family of Thomas Jenkins, a sympathetic and literary sea captain. Jenkins introduced her to the Irish earl Charles John Gardiner, 1st Earl of Blessington, a widower with four children, seven years her senior. They married at St Mary's, Bryanston Square, Marylebone on 16 February 1818. Of rare beauty, charm and wit, she was no less distinguished for her generosity and for the extravagant tastes she shared with her husband, which resulted in encumbering his estates with a load of debt. On 25 August 1822 they set out for a continental tour with Marguerite's youngest sister, the 21-year-old Mary Anne, and servants. They met Count D'Orsay in Avignon on 20 November 1822, before settling at Genoa for four months from 31 March 1823. There they met Byron on several occasions, giving Lady Blessington material for her Conversations with Lord Byron.