What was the surname of Rob Roy?

Rob Roy, byname of Robert MacGregor, (baptized March 7, 1671, Buchanan, Stirlingshire, Scotland—died December 28, 1734, Balquhidder, Perthshire), noted Highland outlaw whose reputation as a Scottish Robin Hood was exaggerated in Sir Walter Scott’s novel "Rob Roy" (1818) and in some passages in the poems of William Wordsworth. He frequently signed himself Rob Roy (“Red Rob”), in reference to his dark red hair.

Rob was a freebooter and was probably also engaged in cattle stealing and blackmail, old and at that time still honourable Highland practices. During the Jacobite (pro-Stuart) rebellion of 1715, he was distrusted by both sides and plundered each impartially. After the rebellion was put down, he was treated leniently because of the intercession of John Campbell, 2nd duke of Argyll. Later, however, Rob was arrested and confined in Newgate Prison, London; he was pardoned in 1727 when about to be transported to Barbados.

In his old age Rob became a Roman Catholic. His letters show that he was well educated; the view of him as a mere brutish highwayman seems not to do him justice.