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 (and during a brief period in 1996, the "High Inquisitor"), 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. The four founders of Hogwarts (Helga Hufflepuff, Godric Gryffindor , Salazar Slytherin , and Rowena Ravenclaw ) are not considered heads, despite leading the school during their time.

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. There can also be more than one deputy headmaster, as the Carrow siblings served under Severus Snape.

Headmasters
Known Headmasters of Hogwarts School of Witchcraft and Wizardry:
 * First Headmaster of Hogwarts (early 11th century)
 * Phyllida Spore (sometime before 1408)
 * Eoessa Sakndenberg (sometime before 1503)
 * Ambrose Swott (sometime around the late Tudor period)
 * Vindictus Veridian (sometime before 1703)
 * 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 (1956-1997)
 * Minerva McGonagall (Acting) (1993)
 * Dolores Umbridge (1996)
 * Minerva McGonagall (Acting) (1997)
 * Severus Snape (1997-1998)
 * Minerva McGonagall (1998-sometime before 2009)

Headmasters from an unknown time period

 * Basil Fronsac
 * Dexter Fortescue
 * Everard
 * Heliotrope Wilkins
 * Quintin Trimble
 * Unidentified Headmaster
 * Unidentified Headmistress
 * Vulpus
 * Limebert
 * Walter Aragon
 * Unidentified Chessmasters and Headmasters of Hogwarts

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

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Goblet of Fire (video game)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Half-Blood Prince (video game)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * Harry Potter and the Deathly Hallows: Part 1 (video game)
 * Harry Potter and the Deathly Hallows: Part 2
 * Harry Potter and the Deathly Hallows: Part 2 (video game)
 * The Tales of Beedle the Bard (real)
 * Lego Harry Potter: Years 1-4
 * Pottermore

Notes and references
Director