McGonagall family

McGonagall is the surname of a wizarding family that was closely tied with Hogwarts School of Witchcraft and Wizardry. It is unknown whether they are Pure-blooded or have both magical and Muggle heritage and ancestry.

Minerva McGonagall
Minerva McGonagall attended Hogwarts at 1937 and was Sorted into Gryffindor House. She became a Prefect in her school years and graduated in 1944, after which she proceeded to replace Albus Dumbledore as Transfiguration Professor, aswell as Head of Gryffindor House. She taught hundreds of students during her time there, while she also assisted the Order of the Phoenix in the war against Voldemort. After the sacking of SEverus Snape, Minerva became the full time headmistress of the school.

M. G. McGonagall
M. G. McGonagall attended Hogwarts School of Witchcraft and Wizardry at the age of eleven in the late 1960s. McGonagall was Sorted into Gryffindor House during the  Sorting Ceremony, the House which was Headed by Minerva McGonagall herself. As such, McGonagall was taught Transfiguration by Minerva aswell. McGonagall also joined the Gryffindor Quidditch team and was awarded a plaque for it in 1971.