Robert Mor Munro, 15th Baron of Foulis (d.1588), and 18th chief of the Clan Munro was a 16th-century Scottish chief. He was known as Robert Mor on account of his large stature. He was the eldest son of Robert Munro, 14th Baron of Foulis. Although this Robert Munro is traditionally 15th Baron and 18th overall chief of the clan, he is only the 8th Munro chief that can be proved by contemporary evidence.
In 1550 Robert Mor Munro, 15th Baron is recorded in a bond of manrent and friendship with George Gordon, 4th Earl of Huntly, chief of Clan Gordon. The document dated 1550 is found amongst the papers in the charter chest of Gordon Castle. However, later Robert Mor Munro would support Mary, Queen of Scots in her feud against the Gordon House of Huntly.
In 1552 Robert Mor Munro sold lands in Wester Fowlis to Margaret Ogilvie, Lady of Moy who was the widow of William MacKintosh, chief of Clan Mackintosh who had been executed at Aberdeen in 1550. In 1553 Queen Mary also granted a Crown charter of the same lands to Margaret Ogilvie. Later, Robert Mor Munro's first marriage would be to Margaret Ogilvie which would bring back to him these lands.
In the Parliament held at Edinburgh on 1 August 1560, amongst the names of those present is "Robert Munro of Fowlis". Robert Mor Munro was a staunch supporter and faithful friend of Mary, Queen of Scots and he consequently was treated favourably by her son James VI. George Buchanan states, that when the unfortunate princess went to Inverness in 1562 and found the gates of the castle shut against her; "as soon as they heard of their sovereign's danger, a great number of the most eminent Scots poured in around her, especially the Frasers and Munros, who were esteemed the most valiant of the clans inhabiting those countries in the north". These two clans took Inverness Castle for the Queen, which had refused her admission. The Queen later hanged the governor, a Gordon who had refused her admission. George Buchanan's original writings state: Audito Principis periculo magna Priscorun Scotorum multitudo partim excita partim sua spoute afferit, imprimis Fraserie et Munoroii hominum fortissimorum in illis gentibus familiae. Which translates in English as: That as soon as they heard of their Sovereign's danger a great number of the ancient Scots poured in around her, especially the Frasers and Munros, which were esteemed the most valiant families inhabiting those countries.