William Alexander (13 April 1824 – 12 September 1911) was an Irish cleric in the Church of Ireland.
He was born in Derry on the 13 April 1824, the third child of the Revd Robert Alexander. He was educated at Tonbridge School and Brasenose College, Oxford. During his time in Oxford he came under the influence of the Oxford Movement. Due to illness his academic record failed to live up to his promise, but he nonetheless displayed a solid scholarship which was to stand him in good stead in later life.
After holding several livings in Ireland, including the Rectories of Fahan, and later Camus-juxta-Mourne (Strabane), he became held the sinecure post of Dean of Emly from 1864 to 1867, resigning it on becoming bishop of Derry and Raphoe, to which see he was nominated on 27 July and consecrated on 6 October 1867. He and three of his brother bishops were the last bishops of Ireland to sit in the Westminster House of Lords before the disestablishment of the Church of Ireland in 1871 by the Irish Church Act 1869. On 25 February 1896 he was translated to become the Archbishop of Armagh and Primate of All Ireland.
In the years 1871 to 1877 he was much involved in the reorganisation of the Church of Ireland and was one of the conservative voices, along with Primate Beresford, Archbishop Trench, and Bishop John Gregg of Cork, that preserved the close identity of the Irish Book of Common Prayer with that of the Church of England. He did however regret some of the more aggressively anti-Ritualist provisions in the Irish Canons, such as that prohibiting the placement of a cross upon the Holy Table. He gave the Bampton Lectures in 1876. An eloquent preacher and the author of numerous theological works, including Primary Convictions, he is best known as a master of dignified and animated verse. His poems were collected in 1887 under the title of St Augustine's Holiday and other Poems.