Headmaster

A Headmaster or Headmistress (or Highmaster, in Durmstrang Institute) is the chief administrator of a School of Magic. They make all major decisions regarding the safety and the day-to-day functioning of the school, and have the power to override any decision made by any other authoritative facilitator at the school, with the possible exception of the Board of Governors, in Hogwarts. A Headmaster also controls the protective spells surrounding the school and the ability for certain individuals to enter or exit the grounds at will.

Hogwarts also has a Deputy headmaster or Deputy Headmistress (depending on gender) that assists the headmaster in his duties. In the event of a headmaster's incapacitation, the deputy headmaster serves as temporary headmaster until the Board of Governors can elect a new, permanent one.

Headmasters
Known Headmasters of Hogwarts School of Witchcraft and Wizardry:
 * First Headmaster of Hogwarts (early 11th century)
 * Eoessa Sakndenberg (sometime before 1503)
 * Amberose Swott (sometime around the late Tudor period)
 * Dilys Derwent (1741-1768)
 * Unidentified Professor (1790s)
 * Phineas Nigellus Black (sometime in the late 19th century to before 1926)
 * Newton Scamander (sometime in the early 20th century)
 * Armando Dippet (early 20th century-1956)
 * Albus Dumbledore (1956-1993)
 * Minerva McGonagall (Acting) (1993)
 * Albus Dumbledore (1993-1996)
 * Dolores Umbridge (1996)
 * Albus Dumbledore (1996-1997)
 * Minerva McGonagall (Acting) (1997)
 * Severus Snape (1997-1998)
 * Minerva McGonagall (1998-before 2017)
 * Headteacher (before 2017-?)

Headmasters from an unknown time period

 * Unidentified Headmaster
 * Professor Everard
 * Dexter Fortescue
 * Professor Vulpus
 * Heliotrope Wilkins
 * Quentin Trimble
 * Basil Fronsac
 * Phyllida Spore

Deputy Headmasters
Known Deputy Headmasters of Hogwarts School of Witchcraft and Wizardry:
 * Minerva McGonagall (after 1956-September 1, 1997)
 * Alecto Carrow (September 1, 1997-May 2, 1998)
 * Amycus Carrow (September 1, 1997-May 2, 1998)

Durmstrang Institute
Known Headmasters of Durmstrang Institute:
 * Unidentified Professor (1790s)
 * Igor Karkaroff (Unknown-1995)

Beauxbatons Academy of Magic
Known Headmasters of Beauxbatons Academy of Magic:
 * Unidentified Professor (1790s)
 * Olympe Maxime (Unknown-Unknown)