William Montacute, 1st Earl of Salisbury (b.1301)
William Montagu, alias de Montacute, 1st Earl of Salisbury, 3rd Baron Montagu, King of Man (1301 – 30 January 1344) was an English nobleman and loyal servant of King Edward III.

The son of William Montagu, 2nd Baron Montagu, he entered the royal household at an early age and became a close companion of the young Prince Edward. The relationship continued after Edward was crowned king following the deposition of Edward II in 1327. In 1330, Montagu was one of Edward's main accomplices in the coup against Roger Mortimer, who until then had been acting as the king's protector.

In the following years Montagu served the king in various capacities, primarily in the Scottish Wars. He was richly rewarded, and among other things received the lordship of the Isle of Man. In 1337, he was created Earl of Salisbury, and given an annual income of 1000 marks to go with the title. He served on the Continent in the early years of the Hundred Years' War, but in 1340 he was captured by the French, and in return for his freedom had to promise never to fight in France again. Salisbury died of wounds suffered at a tournament early in 1344.

Legend has it that Montagu's wife Catherine was raped by Edward III, but this story is almost certainly French propaganda. William and Catherine had six children, most of whom married into the nobility. Modern historians have called William Montague Edward's "most intimate personal friend" and "the chief influence behind the throne from Mortimer's downfall in 1330 until his own death in 1344."