Duchess of Rothesay
Duchess of Rothesay is a Scottish courtesy title. It is held by the wife of the Dukes of Rothesay since the first Duke in 1398. Due to the mortality rate and the fact that very few Dukes of Rothesay were of majority or married prior to ascending the throne (if that), there have in fact been only eight Duchesses of Rothesay. A separate Scottish throne has not existed de facto since 1603 when James VI of Scotland acceded to the throne of England when the House of Tudor died out, creating a personal union. The Act of Union of 1707 united de jure the separate kingdoms and thrones into the Kingdom of Great Britain. The Duchess of Rothesay is the Scottish equivalent of the Duchess of Cornwall. Ever since 1603 the title of The Duchess of Rothesay is held by The Princess of Wales, who was also the Duchess of Cornwall, the title of Duchess of Rothesay is for her use when in Scotland.
Since under current succession law the title of Duke of Rothesay (like that of Duke of Cornwall) can only be held by an heir-apparent who is also the eldest son of the monarch, no woman can be Duchess of Rothesay in her own right. However, this may change if the current proposals to change the rules of succession are completed.
Duchesses of Rothesay 
The eight Duchesses of Rothesay (and the dates the individuals held that title) are as follows:
- Marjorie Douglas (1400–1402) — became dowager duchess when her husband, David Stewart, died as Duke of Rothesay. Majorie died in 1420.
- Caroline of Ansbach (1714–1727) — became queen consort when George II ascended to the throne.
- Augusta of Saxe-Gotha (1736–1751) — dowager when husband Frederick, Prince of Wales died.
- Caroline of Brunswick (1795–1820) — became queen consort on the accession of her husband George IV
- Alexandra of Denmark (1863–1901) — the daughter of Christian IX of Denmark, she became queen consort on the ascension of her husband Edward VII following a 38-year wait on January 22, 1901.
- Mary of Teck (1901–1910) — queen consort upon accession of husband George V. She held the titles of Duchess of York, Duchess of Rothesay, Princess of Wales, Queen-Empress Consort and Queen-Empress Dowager.
- Lady Diana Spencer (1981–1997) — Diana was the first wife of Charles, Duke of Rothesay, currently the person most commonly associated with the title of Princess of Wales. Following her divorce from the Duke of Rothesay, she lost the style HRH and assumed the style of a divorced peeress, that is, her personal name immediately followed by her (former) title. Had Diana remarried, any use of the title Duchess of Rothesay, along with Princess of Wales would have been lost permanently.
- Camilla Shand (2005–present) — the second wife of Charles, Duke of Rothesay, It is intended that Camilla, Duchess of Rothesay/Cornwall, will upon her husband's succession to the throne, become HRH The Princess Consort.
Several Duchesses of Rothesay became queens consort. Those who did not generally took the title of "Dowager Duchesses of Rothesay" after the deaths of their husbands.