Amelia Osborne, Marchioness of Carmarthen

Amelia, Marchioness of Carmarthen
Amelia Osborne, painted by François-Hubert Drouais
Born	Lady Amelia Darcy 12 October 1754
Died	27 January 1784(1784-01-27) (aged 29)
Spouse(s)	Francis Osborne, Marquess of Carmarthen (m. 1773; div. 1779) John "Mad Jack" Byron (m. 1779–84; her death)
Children	George Osborne, 6th Duke of Leeds Mary Pelham, Countess of Chichester Francis Osborne, 1st Baron Godolphin Augusta Leigh
Parent(s)	Robert Darcy, 4th Earl of Holderness Mary Doublet

Amelia Osborne, Marchioness of Carmarthen and de jure 12th Baroness Darcy de Knayth and 9th Baroness Conyers, as well as 5th Countess of Mértola (née Darcy; 12 October 1754 – 27 January 1784), was a British peer and a Portuguese countess.

She was the only child of Robert Darcy, 4th Earl of Holderness, and his wife, Mary Doublet. On 29 November 1773, she married Francis Osborne, Marquess of Carmarthen, and they had three children:

Lord and Lady Carmarthen divorced in May 1779. A month later, she married John "Mad Jack" Byron (father of the poet, Lord Byron) and they had one daughter, Augusta Leigh. A year earlier, Amelia had inherited the right to her father's baronies of Darcy de Knayth and Conyers (although this wasn't confirmed until 1798, long after her death), and she also inherited the Portuguese countship of Mértola from him. On her own death in 1784, the titles were inherited by her eldest son, George.