Dorothy Sidney, Countess of Leicester

Dorothy Sidney, Countess of Leicester (née Lady Dorothy Percy; ca. 1598 – 20 August 1659),^[1] was the eldest daughter of Henry Percy, 9th Earl of Northumberland, and his wife, Lady Dorothy Devereux.^[2] Her sister was the alleged intrigant Lucy Hay, Countess of Carlisle, and their eldest surviving brother was Algernon Percy, 10th Earl of Northumberland.

Dorothy Sidney
Countess of Leicester Lady Dorothy Percy
Dorothy Sidney, by Isaac Oliver
Born	ca. 1598
Died	20 August 1659(1659-08-20) (aged 60–61)
Noble family	Percy
Spouse(s)	Robert Sidney, 2nd Earl of Leicester ​ ​ (m. 1615)​
Father	Henry Percy, 9th Earl of Northumberland
Mother	Dorothy Percy, Countess of Northumberland

Lady Dorothy Percy married Robert Sidney, later Earl of Leicester, in 1615. The couple had twelve children, including:

• Dorothy (1617–1683), married Henry Spencer, 1st Earl of Sunderland.^[3]
• Philip (1619–1697), the 3rd Earl, married Lady Catherine Cecil.
• Henry, created Earl of Romney, died unmarried and without issue.
• Algernon, died unmarried and without issue.
• Robert, died young.
• Lucy (died 1685), married Sir John Pelham, 3rd Baronet.