Elizabeth Annesley, Countess of Anglesey (9 January 1620^[1] – January 1698) was the wife of Arthur Annesley, 1st Earl of Anglesey. They were married on 24 April 1638 in London.^[2] At the time of their marriage, her husband's style was The Hon. Arthur Annesley. In 1660 he inherited his father's title of Viscount Valentia, making Elizabeth a viscountess, and in the following year he was created Earl of Anglesey, making her a countess.

Elizabeth was the daughter and co-heiress of Sir James Altham of Oxhey, Hertfordshire (son of James Altham), and his wife Elizabeth Sutton. The countess's sister, Frances, married Richard Vaughan, 2nd Earl of Carbery.^[3][4]

Elizabeth and her husband had seven sons and six daughters, including:

• James (1645–1690), who succeeded his father to become the 2nd Earl of Anglesey and married (in 1669) Elizabeth, daughter of John Manners, 8th Earl of Rutland and Frances Montagu^[5]
• Altham, who was created Baron Altham in 1681
• Richard (1655–1701), who served as Dean of Exeter, succeeded as 3rd Baron Altham, and married Dorothy, daughter of John Davey, of Ruxford, Devon^[6]
• Arthur
• Charles
• Dorothy, who married Richard Power, 1st Earl of Tyrone (1630–1690) in 1654
• Elizabeth (died 1672), who married Alexander MacDonnell, 3rd Earl of Antrim (1615–1699)
• Frances (1648-1704/5), married first Francis Windham, of Felbrigg, Norfolk, and second (in 1668) John Thompson, 1st Baron Haversham
• Philippa (died 1714/5), married first Charles Mohun, 3rd Baron Mohun of Okehampton,^[7] and second William Coward, of Wells, Somerset
• Anne, who married Sir Francis Wingate J.P. of Harlington Grange, Harlington

The countess died some time in January 1697/8, and was buried at St Anne's Church, Soho.