Louisa Mary Anne Julia Harriet Montagu, Countess of Sandwich (née Lady Louisa Lowry-Corry) (3 April 1781 – 19 April 1862) was an Irish noblewoman and society figure, who in 1804 became the wife of George Montagu, 6th Earl of Sandwich.
She posed for artists including Sir Thomas Lawrence, and her bust was sculpted by Antonio Canova.
Lady Louisa was born on 3 April 1781 in Ireland, the daughter of Irish peer and politician Armar Lowry-Corry, 1st Earl Belmore and Lady Harriet Hobart, daughter of John Hobart, 2nd Earl of Buckinghamshire,Lord Lieutenant of Ireland. She had one half brother, Somerset Lowry-Corry, 2nd Earl Belmore by her father's first marriage to Lady Margaret Butler. She most likely spent part of her early years at Castle Coole, County Fermanagh which her father had rebuilt in 1789.
Her parents' marriage was dissolved by an Act of Parliament in 1793, and the following year her mother married William Kerr, 6th Marquess of Lothian and by him had four additional children. Her father subsequently took Mary Anne Caldwell as his third wife. As a result of her parents' divorce, Louisa was sent to be brought up with one of her relatives, Lady Castlereagh.
Lady Louisa married on 9 July 1804, George John Montagu, Viscount Hinchingbrooke, MP for Huntingdonshire. He succeeded as 6th Earl of Sandwich in 1814, and from that time onwards, Louisa was styled the Countess of Sandwich.
Together they had two daughters and one son, who would succeed his father in the earldom:
In 1818, following the death of her husband, who left her with a large jointure, Louisa moved to the Continent, where she spent many years in the former home of Talleyrand in the Rue de St Florentin in Paris. Afterwards, she retired to a mansion in the Rue de Tivoli.