Hamar katedralskole (English: Hamar Cathedral School) is an upper secondary school in Hamar, Norway.
Founded in 1153 as Schola cathedralis hamarensis, it is the second oldest school in Norway together with Bergen katedralskole and Oslo katedralskole, which were founded the same year, one year after the founding of Trondheim katedralskole. Hamar Cathedral School was founded by Cardinal Nicolas Breakspear, later to become Pope Adrian IV (c. 1100 – 1159). With the Protestant Reformation, Hamar Diocese was closed and in 1602 and the school was merged with Oslo Cathedral School.
The school remained closed until 1876, when it was reopened under the name Hamar offentlige skole for høyere allmenndannelse. The old name was reintroduced in 1936. The current headmaster is Stig Johannessen.
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Per Imerslund (1912–1943), writer
Sigurd Evensmo (1912–1978), writer
Ivar Giæver (1929–), physicist and Nobel Prize in Physics laureate
Knut Faldbakken (1941–), writer
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John Erik Fornæss (1946–) mathematician, Princeton University
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