Sir (Hrothgar) John Habakkuk (13 May 1915 – 3 November 2002) was a British economic historian.
Habakkuk was born in Barry, Vale of Glamorgan, Wales, the son of Evan and Anne Habakkuk. He was named "Hrothgar" after Hroðgar in Beowulf, which his father was reading at the time of his birth. However, he came to be known as John when he started to travel to the United States, and when he was knighted he found it easier to call himself "Sir John" than "Sir Hrothgar". His surname was assumed by a relatively recent forebear after the prophet Habakkuk.
He was educated at Barry County School and St John's College, Cambridge (scholar and Strathcona Student, starredfirst class degree in History 1936). (He was not, as sometimes erroneously stated, connected with Jesus College, Cambridge). He began to study for a PhD under John Clapham, but his progress was interrupted by the Second World War. In 1938, he was elected a Fellow of Pembroke College, Cambridge, a position he held until 1950. He worked in the Foreign Office 1939–42 and the Board of Trade 1942–46, during which period he still found time to carry out research at the Public Record Office and in the archives of country houses. After World War II, he was from 1946 until 1950 Director of Studies and Librarian of the college and Lecturer in the Faculty of Economics. In 1973, Pembroke elected him to an Honorary Fellowship. From 1950 until 1960, he was editor, with Michael Postan, of The Economic History Review.