Claude Nau (died 1605), full name Claude Nau de la Boisseliere, was a confidential secretary of Mary, Queen of Scots in England from 1575 to 1586.
Nau was a successful lawyer practicing in Paris when he was recruited by the Guise family in 1574 to be Mary's secretary. He was presented by the Duke of Guise, Mary's nephew, to Henry III of France who gave him diplomatic accreditation and sent him to Elizabeth I of England. Elizabeth gave a him a letter of introduction to the Earl of Shrewsbury the Scottish Queen's keeper at Sheffield Castle. Nau was frequently mentioned in Mary's correspondence, and many of his own letters survive.
In June 1579, Mary sent Nau as her ambassador to her son, James VI of Scotland, instead of John Lesley, Bishop of Ross. However, the Scottish court at Stirling Castle would not allow him an audience, apparently because Mary's letter was addressed to her son, not the King. Although Nau was accompanied by Nicholas Arrington, Provost Marshall of Berwick upon Tweed, he had no papers from Elizabeth. The Privy Council of Scotland issued a proclamation that he deserved punishment and should be commanded to depart.
Claude's brother, the Sieur de Fontenay, sent from France, had more success. Fontenay was able to meet James VI in August 1584. Fontenay wrote to Claude about his good reception, James had met him in his cabinet at Holyroodhouse, and lent him a horse to join the hunting. In November 1584, Nau spoke with Elizabeth, on the subject of Mary's allegations against Bess of Hardwick. Nau was arrested at Chartley in 1586, but seems to have lived comfortably with the family of Francis Walsingham. After Mary's execution he returned to France where he was exonerated from accusations of treachery to Mary by the King and the Duke of Guise.
Joseph Stevenson discovered Nau's memoirs of Mary and her history and published these works in 1883. Stevenson also attributed a treatise in French on Mary's title to the English throne to Nau. Nau started translating John Lesley's Latin history of Scotland, the De Origine, into French. He did not complete this historical work.
- Stevenson, Joseph, S.J., ed., The History of Mary Stewart, by Claude Nau, Edinburgh (1883)
- Register of the Privy Council of Scotland, vol.3 (1880), 185-6
- HMC, Manuscripts of the Marquis of Salisbury at Hatfield House, vol.3 (1889), 47-62 (French)
- Stevenson, Joseph, (1883), xii-lvii.
- Stevenson, Joseph, (1883), xii, xvii: BL Cotton Titus C.xii fol.1.