Camilla

Camilla's full style, Wikipedia tells us, is:
Her Royal Highness The Princess Charles Philip Arthur George, Princess of Wales and Countess of Chester, Duchess of Cornwall, Duchess of Rothesay, Countess of Carrick, Baroness of Renfrew, Lady of the Isles, Princess of Scotland

The article in Wikipedia continues:
As she is the consort and wife of the Prince of Wales, Camilla legally holds the title and technical rank of Princess of Wales. The Queen has allowed her to use the style of her husband's subsidiary title, Duke of Cornwall, rather than Princess of Wales, except in Scotland, where both Charles and Camilla are formally styled as Duke and Duchess of Rothesay, a title historically associated with heirs to the Scottish throne.

The article goes on:

Clarence House has indicated that when Charles accedes the throne it is intended that she will use the title HRH The Princess Consort, although, as with the example of the Princess of Wales, technically as the wife of a king, Camilla would be Queen. However it is looking increasingly likely that the Duchess would become Queen. To create a position of Princess Consort, it would require new legislation as it is an area of debate as whether the initial position taken by Clarence House is against the constitution.