William de Ros, 3rd Baron de Ros

William de Ros, 3rd Baron de Ros of Helmsley (19 May 1329 – c. 3 December 1352) was a military commander under Edward, the Black Prince. He was knighted by the Black Prince in 1346, having helped raise the siege of Aiguillon. In the same year, he was one of the lords who led the second division in the Battle of Crécy, and afterwards commanded the fourth division of the English army against the Scots, near Neville's Cross, when David Bruce, with many of the Scottish nobles, was taken prisoner.

In 1346, he was with the Black Prince, at the siege of Calais, when it was taken by the English. In 1352, he accompanied Henry of Grosmont, Duke of Lancaster on his journey to Prussia; but died the same year, before the feast of St Michael, aged twenty-six, and was buried abroad.

Marriage

William de Ros married, about 28 August 1339, Margaret de Neville (d. May 1372), daughter of Ralph Neville, 2nd Baron Neville de Raby, by whom he had no issue.

His widow married secondly, as his first wife, Henry Percy, 1st Earl of Northumberland.