Henry Parry (H. P.) Liddon (20 August 1829 – 9 September 1890) was an English theologian. From 1870 to 1882, he was Dean Ireland's Professor of the Exegesis of Holy Scripture at the University of Oxford.
The son of a naval captain, he was born at North Stoneham, near Eastleigh, Hampshire. He was educated at King's College School, and at Christ Church, Oxford, where he graduated, taking a second class, in 1850. As vice principal of the theological college at Cuddesdon (1854–1859) he wielded considerable influence, and, on returning to Oxford as vice-principal of St Edmund Hall, became a force among the undergraduates, exercising his influence in opposition to the liberal reaction against Tractarianism, which had set in after John Henry Newman's conversion to Catholicism in 1845.
In 1864 Walter Kerr Hamilton, the Bishop of Salisbury, whose examining chaplain Liddon had been, appointed him prebendary of Salisbury Cathedral. In 1866 he delivered his Bampton Lectures on the doctrine of the divinity of Christ. From that time his fame as a preacher was established. In 1870 he was made canon of St Paul's Cathedral, London. He had before this published Some Words for God against the scepticism of the day. His preaching at St Paul's soon attracted vast crowds. The afternoon sermon, which fell to the canon in residence, had usually been delivered in the choir, but soon after Liddon's appointment it became necessary to preach the sermon under the dome, where from 3000 to 4000 persons used to gather to hear him.