Katheryn of Berain (Welsh: Catrin o Ferain) (born 1540 or 1541; died 27 August 1591), sometimes called Mam Cymru ("mother of Wales"), was a Welsh noblewoman noted for her four marriages and her extensive network of descendants and relations.
Katheryn was the heiress to the Berain and Penymynydd estates in Denbighshire and Anglesey. She is sometimes referred to as Katheryn Tudor, her father being Tudor ap Robert Vychan and her mother Jane Velville. Her maternal grandfather Sir Roland de Velville (1474 - 25 June 1535) was thought to be an illegitimate son of King Henry VII of England by "a Breton lady".
Katheryn's first husband was John Salusbury (son of Sir John Salusbury, died 1578) of the prestigious Salusbury Family of Lleweni, Denbigh, by whom she had two sons:
- Thomas Salusbury (c.1564 - September 20, 1586). Executed as a traitor for his involvement in the Babington Plot.
- John Salusbury (d. 1612), married Ursula Stanley, illegitimate daughter of Henry Stanley, 4th Earl of Derby and Jane Halsall. Their only surviving son was Sir Henry Salusbury, 1st Baronet, the first of the Salusbury Baronets of Lleweni (1619). Henry was the father of Anne Salusbury, the wife of Arthur Stanhope and ancestor of all the earls of Chesterfield from the fifth Earl.
- Shakespeare's 1601 poem The Phoenix and the Turtle was published in a collection, Love's Martyr (1601), dedicated to Katheryn's son, John Salusbury, who was knighted by Queen Elizabeth in June 1601.
Following his death, she married Sir Richard Clough, an extremely wealthy merchant, by whom she had four daughters:
- Elizabeth Clough (born 1568). Married Roger Salusbury, a brother of John Salusbury and paternal uncle to her older half-brothers. Their only son was John Salisbury.
- Margaret Clough (born 1569). Married William Wynn, A relative of Maurice Wynn.
- Anne Clough
- Katheryn Clough
The Cloughs lived for a time in Antwerp, where Katheryn's portrait was painted, probably by Adriaen van Cronenburgh, as the National Museum now suggests, or perhaps Lucas de Heere, a previous attribution.
Sir Richard died within six years of their marriage, and Katheryn then married Maurice Wynn of Gwydir, who is said to have proposed to her immediately after the funeral of her first husband, only to find that Sir Richard had got in before him. Katheryn had a further two children by Maurice Wynn:
- Henry Wynn. Married Blanche Vaughan.
- Jane Wynn. Married Simon Thelwall.
Her fourth and last husband was Edward Thelwall of Plas-y-Ward, who outlived her. Her many descendants included Hester Thrale and the 18th century explorer John Salusbury.