Thomas Fairfax, third Baron Fairfax of Cameron (1612-1671), commander of the New Model Army, and Lord of Mann after the surrender of the Island in 1651.

He took possession through commissioners rather than in person. The conquest complete, he asserted his right under the Act of Parliament and appointed James Chaloner, William Steane and John Rushworth to enquire into his estate in the Island and its yearly value. On 4 December 1651 they deputed Captains Eaton and Beale to make the enquiries and to notify the tenants of his right. On 17 August 1652 he named commissioners for the government of the Isle: Chaloner, Robert Dynely, and Joshua Witton, minister of the gospel. Early in the following year the Council of State took up the condition of the Island as to its civil government and its security against an enemy, conferred with Chaloner, and was told of Fairfax's intention of sending over a Governor and other well-affected persons. He appointed William Christian, Illiam Dhone, Governor in 1656, the only Manx-born man ever to hold that office, and Chaloner succeeded Christian in 1658.

He is the dedicatee of the first good book about the Island. Chaloner's Short Treatise of the Isle of Man is inscribed to His Excellency Thomas Lord Fairfax, Lord of Man and of the Isles, and the arms of the Island and of Lord Fairfax are engraved on the plates with the map.

He held the Lordship for eight years. By his wife Anne he had an only daughter, who married George Villiers, second Duke of Buckingham, a match that displeased the Protector: the Royalist sympathies of the girl's mother were well known, and it was thought a grave matter that the daughter should ally herself with a nobleman of one of the largest rent-rolls in England. She died in 1704. Fairfax was succeeded as fourth Baron by his cousin Henry, grandson of the first Lord Fairfax, who died in 1693 aged eighty-six without issue.