Julian Henry Francis Grenfell DSO (March 30, 1888 - May 26, 1915), was a British poet of World War I.

Julian Grenfell was born at 4 St James's Square, London. He was the first son and heir of Lord Desborough and Ethel Priscilla Fane.

He was educated at Eton College where he was good friends with Denys Finch Hatton. From Eton he went up to Balliol College, Oxford.

He joined the army in 1910, and was awarded a Distinguished Service Order in 1914.

On May 13, 1915 as a Captain in the Royal Dragoons Julian stood talking with other officers, a shell landed a few yards from them, and a splinter of the shell hit him in the head. He was taken to a hospital in Boulogne where he died of his wounds 13 days later with his mother, father and sister at his bedside. He was 27 years old and was buried at the Boulogne Eastern Cemetery.

The day after his death, together with news of his death, there was published in The Times for the first time his most famous poem 'Into Battle'.

In a letter that was written in October 1914, Grenfell wrote "I adore war. It is like a big picnic but without the objectivelessness of a picnic. I have never been more well or more happy." This letter was infamous when its publications sparked a backlash of arguments that it was naive and that it strengthened propaganda media, which had led to thousands of young men signing up to the British Army, under false pretence.

Julian's younger brother Billy Grenfell was killed in action on July 30, 1915 within a mile of where Julian had been wounded.