Tom Riddle

The Dark Lord Tom Marvolo Riddle, Lord Voldemort, Heir of Slytherin, also known as the Turban, You Know Who or He Who Must Not Be Named, is a wizard currently petrified in the Third Floor Corridor of Hogwarts as of 1993.

List of Soul Shards
While this article covers the history of the "Master Soul" of Riddle, his making of several Horcruxes split his soul into several individuals. They are, as of 1993:
 * Diarymort (inside Tom Riddle's Diary)
 * Voldering (inside the Ring of Gaunt)
 * Locketmort (inside Slytherin's Locket)
 * Cupdemort (inside Hufflepuff's Cup)
 * Ravenmort (inside Ravenclaw's Diadem)
 * Scardemort (inside the body of Harry Potter)

Past
Lord Voldemort's past up until 1991 is identical to his canon self.

1991-1992
Throughout the school-year, Riddle's disembodied spirits had incarnated on the back of Professor Quirinus Quirrell's head so as to secretly infiltrate Hogwarts, hoping to get his nonexistent hands on Nicolas Flamel's Philosopher's Stone, which he planned to use to restore a real body for himself. Riddle's face was hidden by a turban which Quirrell wore constantly.

Harry Potter felt pain in his scar due to Voldemort's presence, but was at a loss to explain it; for most of the year, his friend Hermione Granger mistakenly assumed he was only pretending to get headaches to make fun of how garish and unstylish the turban itself looked.

Later that year, Riddle accidentally gave himself away by speaking Parseltongue in the presence of Parselmouths Hermione Granger and Harry Potter. He was speaking to the Great Basilisk, but his words revealed his intentions to steal what was hidden in the Third Floor Corridor. Believing the voice was actually coming from the turban, a phenomenon they likened to the Sorting Hat, and that the turban was a cursed artifact possessing "poor, innocent Professor Quirrell", Hermione and Harry (along with Ron Weasley) hatched a plan to take the turban off Quirrell and bring it to Professor Albus Dumbledore.

Taking advantage of Dumbledore having momentarily taken leave, Riddle ordered Riddle to infiltrate the Third Floor Corridor. Thanks to Riddle's advice, Quirrell effortlessly beat every challenge until he made his way to the final chamber, where the Mirror of Erised then stood. Before Riddle and Quirrell could devise a way to breach the enchantment keeping the Philosopher's Stone inside the Mirror, the Great Basilisk (who, along with Hermione and the rest of her friends, had followed Quirrell and Riddle into the Corridor) peeked into the room. Quirrell saw her reflection in the Mirror and he and Riddle were thus petrified.

1992-1993
Deciding discretion was the better part of valor, Albus Dumbledore didn't dare to try and move the now stone-like body of Quirrell and Riddle. Instead, he removed the Mirror of Erised from the chamber and refashioned the Third Floor Corridor into a hiding place for the petrified Dark Lord and his minion.

Voldemort and Quirrell's shared body thus remained in the same spot, Petrified and therefore unconscious, for at least a year. In September of 1992, Hermione and her friends, who had come across one of his Horcruxes, decided to place it in the same room as the main Lord Voldemort, and thus put the Diary in Quirrell's pocket.

Personality
Widely considered to be the most dangerous Dark Wizard of all times, Riddle, better known by the title of Lord Voldemort, is a magical genius bent on taking over Britain, and, if possible, the entire world. Arrogant and distrusting, Riddle only puts his confidence in his serpentine friend Nagini and (to a lesser extent) in his most loyal Death Eaters, mostly Bellatrix Lestrange and Severus Snape.