Sir William Paulet (c. 1483 - 10 March 1572) was an English politician who attained several peerages throughout his lifetime - Baron St John (9 March 1539), Earl of Wiltshire (19 January 1550), and Marquess of Winchester (11 October 1551).

Paulet's political career began in 1529, when he became MP for Hampshire. In 1532, he accompanied King Henry VIII to Calais, France, and the following spring, he accompanied the Duke of Norfolk to join King Francois I of France in a proposed audience with the Pope, to discuss Henry's divorce with Catherine of Aragon. In 1536, he was granted the keepership of Pamber Forest , and was soon created Baron St John. He became steward of the bishopric of Winchester, and became a close associate of Cardinal Thomas Wolsey and a friend of Thomas Cromwell. He was also Comptroller of the Royal Household , and held many other high positions.

In 1535 and 1536, he served as one of the judges for the trials of John Fisher, Sir Thomas More, and the alleged accomplices of Anne Boleyn; in 1535, he became Lord Chamberlain. He partially led the royal forces against the Pilgrimage of Grace, a rebellion that broke out in the autumn of 1536, and in 1538, he became Treasurer of the Household. In 1540, he became the master of Henry's Court of Wards and Liveries , a Knight of the Garter in 1543, and Governor of Portsmouth and Lord Steward of the Household in 1545. In 1546, he became Lord President of the Council, and in Henry's will, he was mentioned as one of the eighteen men who would serve as the council of regency during Henry's son's minority.

He continued his political maneuvers in 1550 by supporting the Earl of Warwick against the Duke of Somerset - in reward, he was given the Earldom of Winchester and Somerset's position of Lord Treasurer. When Lord Warwick was created Duke of Northumberland in 1551, Paulet received the Marquessate of Winchester. Six weeks later, he served as Lord Steward in Lord Somerset's trial.

It was said that Northumberland and Winchester "ruled the court" of the minor King Edward VI, and Winchester was accused of supporting Northumberland's attempts to change the order of succession to the English throne (mainly to secure Lady Jane Grey's position on the throne), although he actually strongly opposed it. In March 1554, after Mary I was crowned queen, she affirmed him in all of his positions, although he had been associated with Northumberland (who was eventually executed for treason). After Mary's death, he remained Lord Treasurer and many of his other positions, and even at an advanced age (in 1559, he was over seventy years old), he showed no signs of declining - he was Speaker of the House of Lords in 1559 and 1566. He remained in good standing with the English monarchs - Queen Elizabeth once joked, "for, by my troth, if my lord treasurer were but a young man, I could find it in my heart to have him for a husband before any man in England." Late in life, he opposed any outright support of Protestantism, as he feared it would cause a breach with strongly Catholic Spain.

Winchester died, a very old man, at Basing House in 1572, a house that he held to rebuild and fortify.

|- style="text-align: center;" | width="30%" |Preceded by:
Sir William Fitzwilliam | width="40%" style="text-align: center;" |Treasurer of the Household
1538–1541 | width="30%" |Succeeded by:
Sir Thomas Cheney

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Suffolk | width="40%" style="text-align: center;" |Lord Steward
1544–1551 | width="30%" |Succeeded by:
The Duke of Northumberland

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Suffolk | width="40%" style="text-align: center;" |Lord President of the Council
1546–1550 | width="30%" |Succeeded by:
The Duke of Northumberland

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord Wriothesley
(Lord Chancellor) | width="40%" style="text-align: center;" |Keeper of the Great Seal
1547 | width="30%" |Succeeded by:
The Lord Rich
(Lord Chancellor)

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Somerset | width="40%" style="text-align: center;" |Lord High Treasurer
1550–1572 | width="30%" |Succeeded by:
The Lord Burghley