Agnes Douglas, Countess of Argyll (1574 – 3 May 1607) was a Scottish noblewoman and the first wife of Archibald Campbell, 7th Earl of Argyll. She was the mother of three of his children, including his heir, Archibald Campbell, 1st Marquess of Argyll, the de facto head of the government in Scotland throughout most of the conflict known as the Wars of the Three Kingdoms. Lady Agnes was considered so beautiful that she was described as a "pearl of Lochleven".