John Sinclair, Master of Caithness  John Sinclair, Master of Caithness (d. 1576) was a Scottish nobleman and chief of the Clan Sinclair, a Highland Scottish clan in Caithness. John Sinclair, Master of Caithness was the eldest son of George Sinclair, 4th Earl of Caithness and his wife Lady Elizabeth Graham, daughter of William Graham, 2nd Earl of Montrose. His father, George, Earl of Caithness had feuded with the Earl of Sutherland and the Murrays of Aberscross which had resulted in the Battle of Torran-Roy in 1570 where Caithness was defeated, but returned to besiege the Murrays at Dornoch where several of them were subsequently beheaded. John Sinclair, Master of Caithness was later imprisoned by his father for making peace with the Murrays. The Master of Caithness died at Castle Sinclair Girnigoe in 1576. In 1543, John Sinclair, Master of Caithness had obtained a charter from Mary, Queen of Scots by which the Earldom of Caithness became a "male fee", to him and his male heirs. He married Jean, daughter of Patrick Hepburn, 3rd Earl of Bothwell and had the following children: