Roger de Clifford, 5th Baron de Clifford, ninth Lord Clifford, fifth Baron of Westmoreland (10 July 1333 - 13 July 1389), was the son of Robert de Clifford, 3rd Baron de Clifford (d. 20 May 1344), second son of Robert de Clifford, 1st Baron de Clifford (1273–1314), the founder of the northern branch of the family. His mother was Isabella (d. 25 July 1362), daughter of Maurice, 2nd Lord Berkeley. He succeeded his elder brother, Robert de Clifford, 4th Baron de Clifford in 1350, on which day he made proof of his age.
Clifford entered on his military career when hardly more than twelve, being armed at the time of Jacob van Artevelde's death on 17 July 1345.
In August 1350 he was engaged in the seafight with the Spaniards near Winchelsea; and in 1355 he accompanied his father-in-law, Thomas de Beauchamp, 11th Earl of Warwick, on the expedition to Gascony. He again served in Gascony in 1359, 1360, and in the French expedition of the Duke of Lancaster in 1373.
A document dated at Brougham 10 July 1369 shows him engaging the services of Richard le Fleming and his company for a year. In the same way he retained Sir Roger de Mowbray; and was himself retained, with his company of nearly eighty men, by Edmund Mortimer, 3rd Earl of March, on 25 September 1379.
On 15 March 1361 he was called upon to assist Lionel, duke of Clarence, in his great Irish expedition on pain of forfeiting his Irish estates. A similar summons to defend his lands in Ireland was issued on 28 July 1368.
His chief services, however, were rendered on the Scotch borders. In July 1370 he was appointed one of the wardens of the west marches; but according to Sir H. Nicolas he is found defending the northern borders fourteen years earlier. Resigned the truce with Scotland on 24 August 1369, and was warden of both east and west marches on five occasions between 1380 and 1385.
In August 1385 he accompanied Richard II's expedition against Scotland with sixty men-at-arms and forty archers. His last border sendee seems to have been in October 1388, when he was ordered to adopt measures of defence for the Scotch Marches. In May 1388 he accompanied Richard FitzAlan, 11th Earl of Arundel, in his naval expedition to Brittany.