Tom Marvolo Riddle (born 31 December 1926) was a half-blood wizard and son of wealthy Muggle Tom Riddle Sr. and poor witch Merope Gaunt. His conception was a result of Merope's usage of Amortentia on Riddle Sr, and upon ceasing the use of the potion, he left a pregnant Merope behind. Tom's mother had died while giving birth to him and so he was raised in Wool's Orphanage in London. He is a descendant of Salazar Slytherin, one of the founders of Hogwarts, and had the ability to speak Parseltounge.
Tom began attending Hogwarts School of Witchcraft and Wizardry in 1938 and was Sorted in his ancestor's house of Slytherin. Tom had a particular knack for Defence Against the Dark Arts and would ask loads of questions in the classroom, much to the annoyance of other students. At the beginning of his Second Year, Hogwarts was struck with the news of Dumbledore's escape from prison. This event changed the school as some people Tom had befriended, like Adrian Harper and Lucius Vaisey, felt sympathetic towards Dumbledore and his revolution, putting him at odds with them multiple times.
At odds with many of his friends, Tom broke tradition and began reaching out to Gryffindors, befriending the likes of Minerva McGonagall and Rubeus Hagrid. In Tom's fifth year, he began dating Minerva and upped his studies into Defence Against the Dark Arts as Dumbledore continued ravaging Magical Europe. Tom graduated from Hogwarts in 1945, and not long after, Hogwarts was taken over by Dumbledore, who turned it into a seemingly impenetrable fortress. A militia, led by Gellert Grindelwald, was organized and Riddle helped lead them into battle. During the Battle of Hogwarts, he and Minerva succeeded in bringing Dumbledore's shield down and contributed to his final downfall.
After the war, Tom returned to Hogwarts as the school's Defence Against the Dark Arts professor. He married Minerva McGonagall not long after, and the two had a child; Hadrian Rubeus Riddle, in 1949. Tom continued serving as the school's Defence professor into the 70's, and was one of the few professors to speak against reinstating the Triwizard Tournament. After the retirement of Armando Dippet in 1974, Riddle ascended to the position of Headmaster of Hogwarts, with his wife, Minerva, taking his previously-held position as Deputy Headmaster.