Waitaki Boys' High School is a secondary school for boys located in the northern part of the town of Oamaru, Otago, New Zealand, with day and boarding facilities, and was founded in 1883.^[4] As of 2020^[update], it has a school roll of approximately 400 students.^[5]

The school has a house system with four houses, Don, Forrester, Lee and Sutherland. It organises some cultural activities together with its nearby sister school, Waitaki Girls' High School.

The school is notable for its British colonial architecture, encompassing such historic buildings such as the Hall of Memories, an assembly hall, built to honour its former pupils who died in various wars. Most of the blocks of classrooms at Waitaki Boys High School are named after famous past students, also known as Waitakians or Old Boys. The main, and oldest block of the school is named after Denis Blundell.

The idea of establishing a boys' high school in Oamaru originated with Samuel Shrimski, who was one of the two members of parliament representing the Waitaki electorate.^[6]

The following is a complete list of the rectors of Waitaki Boys' High School:

• Peter Arnett – journalist^[15]
• Fraser Barron – bomber pilot during World War II
• James Bertram – professor, journalist
• Denis Blundell – lawyer, governor-general
• Charles Brasch – poet
• Douglas Carter – former National MP for the Raglan electorate^[16]
• Gonville ffrench-Beytagh (1912–1991) – Dean of Johannesburg and an anti-apartheid activist.
• Sir Malcolm Grant – chairman of NHS England and Chancellor, University of York (former Provost and President of University College London (2003–2013)^[4]
• Ron Guthrey – Mayor of Christchurch (1968–1971)
• Dean Hall – video game designer, mountaineer^[17]
• A. M. Hamilton – engineer
• Brian Henderson – newsreader in Australia^[18]
• Lindsay Merritt Inglis (1894–1966), a senior officer in the New Zealand Military Forces
• Donald Gilbert Kennedy, DSO, Navy Cross (U.S.) (1898–1976) – teacher, colonial administrator and Coastwatcher during the Solomon Islands campaign (World War II).
• Dylan Kennett (1994–) – Olympian and World Champion Track Cyclist
• Douglas Lilburn – Professor, composer
• Robert Macintosh (1897–1989), first Nuffield Professor of Anaesthetics, Oxford
• Terry McCombs – politician, headmaster
• Greg McGee – rugby union player and playwright^[19]
• Ian McLean – politician, economist
• Arnold Nordmeyer (1901–1989) – politician, Labour Party Minister of Finance 1957–1960^[20]
• David Sewell – cricketer^[21]
• Foss Shanahan – diplomat
• Angus Tait – electronics innovator and businessman
• Des Wilson – campaigner in Britain