Henry of Grosmont, Duke of Lancaster (c. 1306–24 March 1361) was a member of the English royal family in the 14th century, and was a prominent English diplomat, politician, and soldier.

Henry was born to Henry of Lancaster, 3rd Earl of Lancaster , and he became a soldier in the English Army. He led various campaigns in Scotland and France (the Hundred Years War), before orchestrating a monumental (but temporary) peace treaty with France. This placed him in favorable light with the King of England, Edward III of England. Throughout his life, he held many honours, including: Earl of Derby, Earl of Lancaster, Earl of Leicester, Earl of Lincoln, and Duke of Lancaster; he was also a founding Knight of the Garter and Lord High Steward to Edward III.

He married Isabel de Beaumont , and they had two children:

• Maud, Countess of Leicester
• Blanche of Lancaster (married John of Gaunt)