Peter Robert Lamont Brown FBA (born 26 July 1935) is an Irish historian. He is the Rollins Professor of History Emeritus at Princeton University. Brown is credited with having brought coherence to the field of Late Antiquity, and is often regarded as the inventor of said field. His work has concerned, in particular, the religious culture of the later Roman Empire and early medieval Europe, and the relation between religion and society.

Peter Brown was born in Dublin, Ireland, in 1935, to a Scots-Irish Protestant family. Until 1939, he spent winter and spring each year in the Anglo-Egyptian Sudan, where his father worked as a railway engineer based at Khartoum. For the rest of the year, he would return with his mother to Bray, in County Wicklow, near Dublin. Following the outbreak of war, Brown and his mother remained in Ireland, though his father did not return finally until 1948. Brown has a stutter and came later in life to be noted as an example of a successful public speaker with a stutter.

Brown has written and spoken about the influence of the Sudanese connection on several occasions. Speaking to the Daily Princetonian, he has remarked:

"Living in the Sudan put in me a love of the Middle East, a real interest in it, distant memories of a very sunny world with large, dark Sudanese servants in long white robes", combined with memories of "hippopotami, crocodiles, and camels under starry skies".

After his father had returned to Ireland, a "handbook of Sudanese Courtesy Customs, containing delicate Arabic phrases of greeting and polite enquiry, was prominent on his bookshelf, as was a deluxe edition of T. E. Lawrence's The Seven Pillars of Wisdom, which I would read, from cover to cover, every time that I returned home on holiday from my school in England." Such influences, with "roots deep in my childhood, already ensured, perhaps, that both religion and the 'exotic' (the non-European and, by implication, the non-classical) were both too large, too ever-present and too rich for their intrusion into the classical world to be dismissed out of hand, as unambiguously negative symptoms of decline. The power of both had begun to puzzle and intrigue me. The collapse of an enlightened empire might, indeed, be a catastrophic event, for all I knew; but it was unlikely to be uninteresting."

Brown was initially educated at Aravon School – now closed but, at that time, a distinguished preparatory school in Bray, County Wicklow, where he first studied Latin and French. Brown was then educated at Shrewsbury School and New College, Oxford. At Shrewsbury, Brown expected to concentrate on sciences, but first studied Ancient Greek and turned in earnest to the study of history:

"I myself had become a keen amateur astronomer, and had re-invented gunpowder to the detriment of my aunt's carpet. I fully intended to enter the Science stream of my new school. My housemaster summoned me to his study. In between puffs of his pipe, he announced with utter certainty: 'Brown, you did too well in [the] Entrance [examination] to do Science. You shall do ... Greek.' And Greek I did, if only for one year, before taking the Junior Certificate and then lapsing from the high calling of a classical scholar in the English Public School tradition into the study of mere History."

When asked to comment on his intellectual formation, Brown has also indicated that he completed his public schooling a year early, returning to Ireland (as he had done for school holidays) in 1952, the year he turned 17. It was then in Dublin that he read Michael Rostovtzeff's § The Social and Economic History of the Roman Empire (1926), which he borrowed from the lending library of the Royal Dublin Society at Ballsbridge. The academic year 1952–1953 was a "hiatus" for Brown, between school and university, during which he learned to type at a secretarial school, and received German lessons from an academic at Trinity College Dublin who had been a refugee from Nazi Germany.