Mary Sidney was the daughter of Henry Sidney and Mary Dudley. She was born on 27 October 1561 at Tickenhall near Bewdley in Worcestershire. She was well educated, which was unusual for a girl at the time. She knew French, Italian, Latin and Greek. When she was fifteen, she married Henry Herbert, Earl of Pembroke. Thus she became Countess of Pembroke. She had four children, Katherine, Anne, William and Philip. She died of smallpox in London on 25 September 1621. She is buried in the cathedral in Salisbury.