Lucy Walter, also known as Lucy Barlow, was the first mistress of King Charles II of England and mother of James, Duke of Monmouth. During the Exclusion Crisis, a Protestant faction wanted to make her son heir to the throne, fuelled by the rumour that the king might have married Lucy, a claim which he denied.

Charles II was King of Scotland from 1649 until 1651 and King of England, Scotland, and Ireland from the 1660 Restoration of the monarchy until his death in 1685.