Nicholas Langrishe Alleyne Lash (born 1934) is an English Roman Catholic theologian. After serving in the British Army, and working for a short while as a Roman Catholic priest, he held for twenty years the post of Norris-Hulse Professor of Divinity in the University of Cambridge from 1978 to 1999, succeeding Donald MacKinnon, and being succeeded by Denys Turner.
Nicholas Lash is the author of numerous theological books, and a regular contributor to The Tablet. A Roman Catholic, and considered a liberal, Lash has voiced strong but measured criticism of practices among leading figures in his tradition, arguing for open debate on a variety of topics, including the ordination of women.
He is reportedly one of the few Roman Catholic theologians who have read, slowly, the whole of Karl Barth's Church Dogmatics and the whole of Karl Rahner's Theological Investigations. One of Lash's strongest intellectual influences seems to have been the recovery of Aquinas's theology, using forms of philosophical argument influenced by Ludwig Wittgenstein, which became influential in the 1970s, associated with Cornelius Ernst and Fergus Kerr. Arguably his most significant piece of writing is also one of his shortest, his reflections on the Apostles' Creed, which includes discussion of the doctrine of the Trinity.
Lash was born to Joan Mary Moore, a Roman Catholic of Irish descent, and Brigadier Henry Alleyne Lash, a Protestant officer in the British Indian Army. His sister was writer Jini Fiennes, who had seven children, including actors Ralph and Joseph Fiennes, filmmakers Sophie and Martha Fiennes, and musician Magnus Fiennes. He also had a brother, Ephrem Lash, who was an Eastern Orthodox archimandrite and prominent translator of patristic texts.