Margaret Holland (1385–30 Dec 1439) was the daughter of Thomas Holland, 2nd Earl of Kent, who was the son of Joan "the Fair Maid of Kent" (granddaughter of Edward I of England, wife of Edward the Black Prince and mother of Richard II of England). Margaret married John Beaufort, 1st Earl of Somerset, son of John of Gaunt, 1st Duke of Lancaster and his mistress Katherine Swynford. They had six children:
- Henry Beaufort, 2nd Earl of Somerset (c. 1401–25 Nov 1418).
- John Beaufort, 1st Duke of Somerset (baptized 25 March 1404–27 May 1444).
- Thomas Beaufort, Earl of Perche (c. 1405–1432).
- Joan Beaufort (c. 1406–15 July 1445), who married James I of Scotland and Sir James Stewart, the Black Knight of Lorn.
- Edmund Beaufort, 2nd Duke of Somerset (c. 1406–22 May 1455).
- Margaret Beaufort, Countess of Devon (c. 1409–1449). Married Thomas de Courtenay, 13th Earl of Devon.
After Beaufort died in 1410 (in the Tower of London), she married his half-nephew Thomas Plantagenet, Duke of Clarence, the son of King Henry IV. They had no children. Margaret and both her husbands are buried together in a carved alabaster tomb in Canterbury Cathedral that shows her lying between the two of them.
