Professor Severus Snape (9 January, 1960 – 2 May, 1998) was a half-blood wizard who was the son of the witch Eileen Snape (née Prince) and Muggle Tobias Snape. During his lifetime, Severus Snape was Potions Master (1981–1996), Defence Against the Dark Arts professor (1996-1997), and Headmaster (1997-1998) of Hogwarts School of Witchcraft and Wizardry (which he attended as a student from 1971 until 1978). He was also member of the Order of the Phoenix and played a very important role in both of the Wizarding Wars against Lord Voldemort.

Shortly before Lily Evans was killed by Lord Voldemort, Snape changed sides and became a member of the Order of the Phoenix and double agent during the Second Wizarding War. With tremendous difficulty, Snape was able to prevent Lord Voldemort from learning the truth about his loyalties. Despite the opinions of most others, Albus Dumbledore trusted Snape for reasons that were kept between them both until their deaths. Upon his death, it was revealed that his deep, strong love for Lily Evans caused him to redeem himself, joining Dumbledore's cause at the prospect of her protection from Lord Voldemort.

The relationship between Dumbledore and Snape would be one of an unusually strong loyalty, so much so that Snape agreed to kill Dumbledore upon Dumbledore's own request. Before Dumbledore's death, Snape promised to protect the students of Hogwarts from the Death Eaters.Snape later participated in the Battle of Hogwarts, but was killed by Lord Voldemort who mistakenly believed that Snape was the master of the Elder Wand.