| Honorific Prefix: | His Grace |
| The Duke of Northumberland | |
| Birth Name: | Henry George Alan Percy |
| Birth Date: | 15 July 1912 |
| Death Place: | Pecq, Belgium |
| Death Cause: | Killed in action |
| Resting Place: | Esquelmes War Cemetery |
| Office: | Parliamentary Private Secretary |
| Term Start: | 1935 |
| Term End: | 1940 |
| Commands: | 3rd Battalion Grenadier Guards |
Henry George Alan Percy, 9th Duke of Northumberland (15 July 1912 – 21 May 1940) was the son of Alan Percy, 8th Duke of Northumberland and Lady Helen Gordon-Lennox.
He served as Parliamentary Private Secretary to the Lord Privy Seal in 1935.[1] During his lifetime, the 9th Duke was considered one of Britain's most eligible bachelors.
He was killed at Pecq in Belgium, serving with the 3rd Battalion Grenadier Guards during the retreat to Dunkirk. His body is interred in the Esquelmes War Cemetery.[2]
He was succeeded as Duke of Northumberland by his brother Hugh Percy, 10th Duke of Northumberland. A posthumous portrait by Oswald Birley is now displayed at the family seat of Alnwick Castle.