Lord Voldemort

Birth and adolescence
Born Tom Marvolo Riddle in 1926, Lord Voldemort was the son of the Muggle (non-magical) Tom Riddle Sr and the witch Merope Gaunt. Through his mother, he is the last descendant of the powerful wizard Salazar Slytherin. Through his father, he is a descendant of the Riddles of Little Hangleton, a Muggle family. His mother, Merope, had used a love potion means to persuade the elder Riddle to marry her. Later on when Merope stopped feeding the potion to Riddle, she and her unborn child were abandoned by Riddle.
One New Year's Eve night, Merope wandered into an orphanage in London when she suspected she was about to enter labour. After giving birth, Merope asked the matron to name her son Tom, after his father, and Marvolo, after his maternal grandfather, Marvolo Gaunt, and died within the hour.
Riddle was raised at the orphanage. From an early age, he showed great magical abilities — primarily psychokinesis — and extraordinary insensitivity. At school, he was very gifted and showed a great thirst for knowledge, and he was previously known as a bully who tortured other children in his orphanage largely for fun.
It was Dumbledore's duty to visit Riddle when he reached the age of 11 and invite him to study at Hogwarts. By that time he already showed great potential as a magic-user; he could move things with his mind, make animals do his bidding, speak with snakes, cause people pain, and, in his own words, "make bad things happen to people who annoy[ed him]." However, he also displayed cruelty, a disregard for others, a need for absolute and total control and a lack of moral judgment.
In his first meeting with Dumbledore, Riddle was seen to be a sharply intelligent and calculating boy with a cold, smoothly expressionless face intended to prevent others guessing what he was thinking. He was sure that he was born to be different, and detested his name "Tom," which he deemed to be too common. He also demonstrated a hunger for power when Dumbledore proved that magic was real to him, by setting his wardrobe on fire and then extinguishing the flames, without any harm done.
His magic wand was made of yew, a wood associated with death and rebirth, which has innate destructive workings and is well suited for use in transfiguration. It is 13½ inches long and has the feather of a phoenix at its core. The wand's maker, Mr Ollivander, got this feather from Dumbledore's pet phoenix, Fawkes. Fawkes gave just one other feather to be used in a wand, and coincidentally this wand "chose" to belong to Harry Potter.
Riddle attended Hogwarts from 1938 to 1945 and was sorted into Slytherin house. He was an extremely handsome and gifted student, and became a staff favourite. He was made a Prefect and eventually the Head Boy. He was described by Albus Dumbledore as "the most marvelous student ever to pass through Hogwarts". However, Dumbledore never forgot the enjoyment in cruelty that Riddle had confessed to him on their first meeting, and never fully trusted him. During holidays he was obliged to return to the orphanage, which he hated. He quickly gathered a group of followers, particularly fellow Slytherin students, whom he referred to as "friends", but for whom he is said to have felt little or no compassion. Many of these people, and later on, their sons, were to become what he termed Death Eaters; he is shown to have at least a two generation influence over the Avery and Lestrange families. Riddle and his friends started their trouble-making while at Hogwarts; Dumbledore states that during the time they were at school, a series of incidents occurred to which the answers were never satisfactorily linked. It was around this time that Riddle began using the name Lord Voldemort among his followers; "I am Lord Voldemort" is an anagram of his full name, Tom Marvolo Riddle (see Anagram).
In 1942, the summer before his fifth year at Hogwarts (or, as Dumbledore phrased it, in the summer of his sixteenth year), Riddle returned to Little Hangleton, hoping to meet his maternal grandfather, Marvolo Gaunt, and confirm that he was a descendant of the Gaunts, and, through them, Slytherin. Instead, he met his uncle Morfin, learning of his grandfather's death and his father's non-magical nature. He stole an heirloom ring from Morfin, and, upon learning that his father was still alive and had abandoned his mother, murdered him as well as his father's Muggle parents. He framed Morfin for the murders by modifying his memory so that Morfin believed he was the murderer. Morfin confessed this to the Ministry of Magic, and was eventually found responsible by trial. Frank Bryce, the Riddles' gardener, fell under suspicion from the muggle police, as the door to the Riddle House had not been forced and Bryce was the only person with keys to the house. The cause of death could not be determined, however, due to the fact that the Killing Curse leaves the victim lifeless with no signs of any struggle, wound, or medical problem, and Bryce was released, though he was regarded with suspicion by the other villagers until his death in 1994 at the hand of Voldemort. In this way, two men were blamed for the Riddle murders and Riddle kept the Gaunts' ring and returned to Hogwarts for his fifth year.
During Riddle's fifth year at Hogwarts, in 1942–1943, he opened the Chamber of Secrets, created by his ancestor Salazar Slytherin, which led to the .[HP6] Instead, he used Rubeus Hagrid's possession of an acromantula to frame him for the crime, and got the boy expelled.
In his fifth to seventh years at Hogwarts he became even more obsessed with immortality. Some time in either his fifth year, or the first term of his sixth year, Riddle questioned Slughorn about Horcruxes. Riddle successfully fooled the professor into thinking that it was only for school work or for "further knowledge", and Slughorn explained why and how Horcruxes were created.
death of a muggle-born student named Myrtle. Only Dumbledore ever suspected him,[HP2] as Riddle had exercised his considerable charm over most of the other staff, including Potions Master Horace Slughorn
Pursuit and creation of horcruxes
Tom Riddle's diary, a Horcrux.
Following his graduation, Riddle applies to headmaster Armando Dippet for the teaching post of Defence Against the Dark Arts. Dippet turns Riddle down, but invites him to reapply in several years. Riddle subsequently seeks employment at Borgin and Burkes, a shop renowned for its inventory of Dark Arts relics, even though his teachers thought that he could have done much better. Shortly before disappearing from this post, Riddle murders an old woman by the name of Hepzibah Smith, in order to disguise the theft of two priceless wizarding relics from her: a locket belonging to Salazar Slytherin and a cup once belonging to Helga Hufflepuff. As with his murder of his Muggle family, Riddle modifies the memory of a nearby innocent to make them take credit for the death — in this case, Hepzibah's decrepit house elf Hokey.
Riddle then mysteriously disappears and immerses himself totally in the Dark Arts. Decades later, he re-emerges as the horrifyingly mutated Lord Voldemort, having literally split his soul into seven pieces, before securing six of these pieces inside items called Horcruxes, in order to make him immortal. His school diary is one of them, along with Marvolo Gaunt's ring, Salazar Slytherin's locket, Helga Hufflepuff's cup, the snake Nagini and Rowena Ravenclaw's diadem. He returns to Hogwarts and once again asks to teach Defence Against the Dark Arts. He is turned down again, this time by Albus Dumbledore (who had become Headmaster in the interim). Dumbledore suspects that Voldemort wants to return to Hogwarts to establish his power over a new generation of students, as he had done during his own school years, and to search for more relics of the Hogwarts founders.
First war
In the year 1970, Voldemort begins to terrorise the entire Wizarding World, obsessed with purifying the wizard race and removing "Muggle-born" wizards. He finally turns on every wizard who tries to oppose him, using murder, torture and intimidation. He finds a small group of like-minded wizards, whom he calls the Death Eaters, to do his bidding. He forces multiple Ministry of Magic personnel under the Imperius Curse, in order to infiltrate the Wizarding governing body. Panic and fear spreads throughout the entire Wizarding community, and Dumbledore forms the Order of the Phoenix to combat this new threat. The Order is composed of some of the greatest aurors in Great Britain. They work tirelessly against Voldemort, whose followers in return capture, torture, and kill many of them.
Up to 1980, seemingly unstoppable against the forces of the Ministry of Magic and the Order of the Phoenix, Voldemort nearly achieves total domination of the Wizarding community, before making a mistake that causes him to lose it all.
First downfall
One night, in the Hog's Head in Hogsmeade, Dumbledore interviews Sybill Trelawney for the post of Divination teacher at Hogwarts. At first, Dumbledore is unimpressed, until Trelawney makes a genuine prophecy concerning Voldemort:
"The one with the power to vanquish the Dark Lord approaches... born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must die at the hand of the other for neither can live while the other survives... the one with the power to vanquish the Dark Lord will be born as the seventh month dies..."
Young Death Eater Severus Snape overhears the first part of the prophecy, but does not hear from "'and the Dark Lord will mark him as his equal'", onwards. When Dumbledore discovers Snape, the latter flees with flawed knowledge of Voldemort's fate.
After Snape informs Voldemort of the prophecy, Voldemort realises that the prophecy must refer to either Neville Longbottom or Harry Potter, as they are "both born at the end of July that year, both of whom had parents in the Order of the Phoenix, both sets of parents having narrowly escaped Lord Voldemort three times." Voldemort decides that the prophecy is about Harry, a half-blood wizard, rather than Neville, the pure-blood, perhaps seeing some of himself in Harry. Upon hearing that Voldemort intends to kill the Potters, Snape regrets having told Voldemort the prophecy, as Snape has been in love with Lily Evans (now Lily Potter) since they were childhood neighbours. Snape flees to Dumbledore to inform him of Voldemort's plans, and Dumbledore acts immediately, telling the Potters to cast a Fidelius Charm to protect the location of their home from Voldemort. James Potter first intends to choose Sirius Black as his Secret Keeper, but Sirius persuades James to switch to Peter Pettigrew at the last minute, saying Voldemort is less likely to come after Pettigrew. Unbeknownst to James, Pettigrew has joined Voldemort's army of Death Eaters, and so delivers the secret location of the Potter house right to the Dark Lord himself.[
Voldemort goes to Godric's Hollow to destroy the boy who he believes would be his downfall: Harry Potter. He promptly murders James Potter, but then makes a crucial mistake; he challenges Harry's mother, Lily, to step aside, but she does not, giving Harry the ultimate protection of love.Voldemort had not intended to murder Lily, but after she refuses his offer to stand aside, he kills her. He then turns his wand on Harry and performs the Killing Curse, but due to the protection, the spell rebounds upon him, instantly destroying his body and a portion of the house. The backfired spell leaves him alive, but in a form "less than the meanest ghost", his Horcruxes having prevented his total death. Unknown to even Voldemort himself, and only correctly hypothesised by Dumbledore, Voldemort's soul is so unstable that a piece of it clings to the last living being in the structure, Harry Potter. This inadvertantly makes Harry Voldemort's seventh Horcrux and grants him some of Voldemort's powers, such as the ability to converse with snakes.
His body and power destroyed, Voldemort can only possess the bodies of animals, especially snakes, but his possession drastically shortens their lives. He takes refuge in dark forests in Albania, until he encounters Professor Quirrell, whom he promptly possesses. This enables Voldemort to return to Great Britain, where he begins his plans to regain both a body and his power.

Connections with Harry Potter
Voldemort disembodies himself when his Killing Curse targeting Harry Potter rebounds on him. Due to his numerous murders, the rebounce had caused a fragment of his soul to separate and latched onto Harry, making Harry an unintended Horcrux. After this, he and Harry are connected in several ways. Throughout the whole series, Harry's scar burns when he senses Voldemort nearby; in The Goblet of Fire Harry first discovers that he can access Voldemort's thoughts and emotions, and from then on whenever Voldemort was extremely angry, happy or in pain, Harry's scar burns painfully. Voldemort discovers their connection in Harry Potter and the Order of the Phoenix and uses it to lure Harry into the Department of Mysteries to recover Sybill Trelawney's prophecy. This connection ended when Voldemort used the Aveda Kedavra in the Forbidden Forest against Harry, killing the bit of soul within Harry while leaving Harry merely unconscious..