Durham School is a fee-charging boarding and day school in the English public school tradition located in Durham, North East England. Since 2021 it has been part of the Durham Cathedral Schools Foundation.

Durham School was an all-boys institution from its foundation in 1414 until 1985, when girls were admitted to the sixth form. The school takes pupils aged 3–18 years and became fully co-educational in 1998.

A member of the Headmasters' and Headmistresses' Conference, it enrolls 495 day and boarding students. Its preparatory institution, known as the Chorister School, enrolls a further 250 pupils.

Durham and Bow's former pupils include politicians, clergy and British aristocracy. Former students are known as Old Dunelmians. Founded by the Bishop of Durham, Thomas Langley, in 1414, it received royal foundation by King Henry VIII in 1541 following the Dissolution of the Monasteries during the Protestant Reformation. It is the city's oldest institution of learning.

The history of Durham School can be divided into four sections. Firstly there is the time from its founding by Langley in 1414, then in 1541 Henry VIII refounded it, the period from 1844 when the school moved from its site on Palace Green to its current location across the river Wear, and finally from 2021 when the school became part of the Durham Cathedral Schools Foundation.

The school is often referred to in histories and the Oxford Dictionary of National Biography as "Durham Grammar School". It should not be confused with the Chorister School in Durham, which merged with Durham School in 2021 to form the Durham Cathedral Schools Foundation. There is strong recorded evidence of the existence of the school pre-1414, for example Simon of Farlington an Archdeacon of Durham, gave the manor of Kyhou (Kyo) to the Almoner of Durham Cathedral Priory in 1180 'for the maintenance of 3 scholars of Durham School...'

Durham School was founded by Thomas Langley in 1414, which was the foundation date accepted by the Clarendon Commission into public schools in 1861, making it the 18th oldest in Britain. It is possible, however, that it may actually have origins in the Priory at Lindisfarne, being moved to Durham City to escape marauding Viking invaders around the time that St. Cuthbert's body was brought to what is now the site of Durham Cathedral. The school was in Langley's time situated on the east side of Palace Green to the north of the cathedral.

At the time of the Dissolution of the Monasteries during the Protestant Reformation in 1541, the school was refounded by Henry VIII. It remained in the same location, indeed the Headmaster Henry Stafford remained in post, during this period. In 1640 the "old School Buildings were utterly destroyed by the Scots, and the Head Master [Richard Smelt] retired to his Rectory of Easingwold where he took pupils" and the School was "recognised and endowed by the Parliamentary Commission 1652-3". Homeless due to the burning down of its buildings, the school continued in various houses in the city.