| Louisa Petty, Marchioness of Lansdowne | |
| Death Date: | 7 August |
| Father: | John FitzPatrick |
| Relatives: | Richard FitzPatrick (brother) Mary FitzPatrick (sister) John FitzPatrick (brother) Richard FitzPatrick (grandfather) John Leveson-Gower (grandfather) |
| Children: | 2, including Henry |
Louisa Petty, Marchioness of Lansdowne (; later Petty Fitzmaurice; 1755 - 7 August 1789), known as the Countess of Shelburne from 1779–84, was an Anglo-Irish aristocrat from the Mac Giolla Phádraig dynasty. She was the wife of Prime Minister William Petty, 2nd Earl of Shelburne.[1]
The Marchioness was the youngest daughter of John FitzPatrick, 1st Earl of Upper Ossory, and his wife, Lady Evelyn (née Leveson-Gower; daughter of John Leveson-Gower, 1st Earl Gower).[2]
Her eldest brother was John FitzPatrick, 2nd Earl of Upper Ossory. She had a younger brother Richard, who also became a noted statesman and soldier, and an elder sister, Lady Mary Fox (Baroness Holland), the subject of paintings by Thomas Gainsborough, Sir Joshua Reynolds, and Pompeo Batoni.[2] [3]
She married, as his second wife, William Petty, 2nd Earl of Shelburne, who served as Prime Minister for 10 months in 1782 - 83, and was afterwards created Marquess of Lansdowne. The couple were married on 8 July 1779
She died on 7 August 1789.