James Hamilton, 3rd Earl of Arran (1537–1609) was a Scottish nobleman and soldier who opposed the French-dominated regency during the Scottish Reformation. He was the eldest son of James Hamilton, Duke of Châtellerault, sometime regent of Scotland. He was of royal descent, and at times was third or fourth in succession to the Scottish crown; several royal marriages were proposed for him, but he eventually never married. He went to France with Mary, Queen of Scots, where he commanded the Scots Guards. After returning to Scotland, he became a leader of the Protestant party against Mary and her French supporters. However, he went insane in 1562 and was confined for the rest of his life.

The Scottish Reformation was the process whereby Scotland broke away from the Catholic Church, and established the Protestant Church of Scotland. It forms part of the wider European 16th century Protestant Reformation.