Professor Minerva McGonagall was a half-blood witch who served as Professor of Transfiguration, Head of Gryffindor House, Deputy Headmistress, and later Headmistress of Hogwarts School of Witchcraft and Wizardry. A formidable and exceptionally talented witch, McGonagall was a registered Animagus and a key member of the Order of the Phoenix during both the First and Second Wizarding Wars. Known for her strict, no-nonsense demeanor, she was also fiercely protective of her students and a staunch supporter of Albus Dumbledore. She played a crucial role in the defense of Hogwarts during the final battle against Lord Voldemort.
Minerva McGonagall was born in Scotland to a Muggle Presbyterian minister, Robert McGonagall, and a pure-blood witch, Isobel Ross (Pottermore). Upon receiving her Hogwarts acceptance letter, her magical abilities were revealed to her family, causing a rift between her parents (Pottermore). At Hogwarts, she was a Hatstall, with the Sorting Hat taking five and a half minutes to decide between Gryffindor and Ravenclaw before ultimately placing her in Gryffindor (Pottermore). She excelled as a student, becoming a Prefect and Head Girl, and achieving top grades in her O.W.L.s and N.E.W.T.s (Pottermore).
After graduating from Hogwarts, McGonagall worked for two years at the Ministry of Magic in the Department of Magical Law Enforcement (Pottermore). Unhappy with the anti-Muggle prejudice at the Ministry, she returned to Hogwarts to accept a teaching position in the Transfiguration department under its head, Albus Dumbledore (Pottermore). She eventually became Head of the department. During the First Wizarding War, she was a member of the original Order of the Phoenix, fighting against Lord Voldemort and his Death Eaters. On the night the Potter family was attacked in Godric's Hollow, she was the first to arrive at Number Four, Privet Drive, observing the Dursleys all day in her cat form before Dumbledore and Rubeus Hagrid arrived with the infant Harry Potter.
In the years following Voldemort's first downfall, McGonagall continued her roles as Professor of Transfiguration and Head of Gryffindor. She greeted Harry Potter and his fellow first-years upon their arrival at Hogwarts in 1991. Despite her strictness, she showed a softer side, particularly towards Harry; recognizing his innate talent for flying, she bent school rules to get him a Nimbus 2000 and a spot on the Gryffindor Quidditch team as Seeker. She contributed to the protection of the Philosopher's Stone by creating a giant, enchanted Wizard's Chess set.
With the return of Lord Voldemort, McGonagall rejoined the Order of the Phoenix. She fiercely opposed Dolores Umbridge's tyrannical reign as High Inquisitor of Hogwarts, openly challenging her authority and defending students from her cruel punishments. During the O.W.L. astronomy practical, she was hit by four simultaneous Stunning Spells while attempting to defend Hagrid from Ministry Aurors and was sent to St Mungo's Hospital for Magical Maladies and Injuries to recover. After Dumbledore's death, she became the Acting Headmistress of Hogwarts. During the subsequent school year under the control of Severus Snape and the Carrows, she remained at the school to protect the students as best she could. During the Battle of Hogwarts, McGonagall took command of the school's defense. She used a powerful Piertotum Locomotor spell to animate the school's statues and suits of armour to fight. She dueled Severus Snape in the Great Hall, forcing him to flee, and later courageously fought Lord Voldemort himself alongside Kingsley Shacklebolt and Horace Slughorn. Following the battle and Voldemort's final defeat, she became the permanent Headmistress of Hogwarts.
Professor McGonagall is described as a tall, severe-looking witch who often wears her black hair in a tight bun. She frequently wears emerald green robes and has a very stern expression. She also wears square-rimmed spectacles which, in her Animagus form as a silver tabby cat, manifest as distinctive square markings around her eyes. Her personality is a blend of strict discipline and deep-seated fairness and courage. She rarely shows emotion, but her loyalty to Dumbledore and her protectiveness over her students, especially Harry Potter, Ron Weasley, and Hermione Granger, are unwavering. She possesses a dry sense of humor that appears on rare occasions, often in moments of triumph over adversaries like the Dursleys or Dolores Umbridge. She does not tolerate foolishness or rule-breaking but is willing to bend the rules when she believes it is for the greater good.