Sir Alexander Holborne of Menstrie (died January 22, 1772) was a Scottish baronet and sea captain.

He was the second but first surviving son of the advocate James Holborne(son of Major General Holborne) by his second wife Jean, the daughter of Alexander Spital of Leuchat, and succeeded to the baronetcy on the death of his brother in 1757/8.

Admiral Saunders, upon leaving the Mediterranean in 1757, took his chaplain, his flag captain Alexander Hood, and all six of his lieutenants, among whom then served Alexander Holborne, later promoted to captain. The presence of Hood, a follower of Admiral Smith, and Holborne, illustrates the common practice among patrons of swapping recommendations.

Sir Alexander had been a captain in the Royal Navy, but later appears to have been embroiled in an intrigue that remains a mystery. For reasons unknown, he was for many years imprisoned by the King’s Bench, and was apparently unknown in Edinburgh some ten years before his actual death at Southwark, where he had been confined to lodgings called "Harrow Dunghill" at Southwark.

Alexander, (Baron after the death of his brother James) was to be declared dead a full decade before his time was up! It is clearly stated in the testament of Sir Alexander's daughter, Lady Jean Holborne, that she, confirmed by the Commissary of Edinburgh, acknowledged her father was dead in 1762. Her mother (unnamed) remained as his "widow" for twelve years and did not remarry until in 1774, two years after his actual death, when she was wed to John Graham, a Newcastle surgeon. Sir Alexander's daughter, Lady Jean Holborne, seems to have kept whatever secret led him to his final disposition, imprisoned and forgotten by his brothers and kin. He died apparently insane.

The original King's Bench Prison (at Southwark) was demolished in 1754. Alexander was serving under Admiral Hood in the Mediterranean in 1757 and so would have been housed in the new building during his later incarceration. Looking for the probable date of his admission, given he was recorded as dead by his daughter in 1762, this could in fact be the year he was imprisoned. It is reasonable to assume on the record of his ambitous brother the Admiral Sir Francis that Alexander was imprisoned to allow the family title to fall to the third son (Francis), who had lied about his age if existing records are to be belived.