Arthur Henry Hallam (1 February 1811 – 15 September 1833) was an English poet, best known as the subject of a major work by his best friend, Alfred, Lord Tennyson. Hallam has been described as the jeune homme fatal (French for fatal young man) of his generation.
In October 1828, Hallam went up to Trinity College, Cambridge, where he met Tennyson. Both joined a group known as the Cambridge Apostles. Their shared interests led to a close friendship, and Arthur became engaged to Tennyson's sister, Emilia Tennyson in 1832. While travelling abroad with his father, he died suddenly at Vienna, of a brain hemorrhage.
Hallam's death was a significant influence on Tennyson's poetry. Tennyson dedicated one of his greatest poems to Hallam (In Memoriam A.H.H.), and stated that the dramatic monologue "Ulysses" was "more written with the feeling of [Hallam's] loss upon me than many poems in [the publication] In Memoriam". Tennyson named his elder son after his late friend. Emilia Tennyson also named her elder son Arthur Henry Hallam in his honor.