In a 2001 interview, Rowling said Voldemort was invented as a nemesis for Harry Potter (the protagonist of the novels), and she intentionally did not flesh out Voldemort's backstory at first.
"The basic idea [was that Harry] didn't know he was a wizard ...
He is the leader of the Death Eaters, a group of evil wizards and witches dedicated to ridding the Wizarding World of Muggles and establishing Voldemort as its supreme ruler.
According to Rowling, the 't' in "Voldemort" is silent, Jim Dale pronounced it so in the first four US audiobooks, yet the characters in the film version of Harry Potter and the Philosopher's Stone pronounced the "t"—after which Dale changed his audiobook pronunciation accordingly.
In this story, Rowling introduces him as the Dark Lord who murdered Harry's parents, James and Lily, but as a result of his mother's love and willingness to sacrifice herself for him, baby Harry survives when Voldemort tries to murder him with a Killing Curse.
Voldemort is disembodied, and Harry carries a mysterious scar on his forehead as a result.
In this book, Ginny is written as a shy girl with a crush on Harry.
He killed Harry's parents, and then he tried to kill Harry—he tried to curse him. So he's left with this lightning bolt shaped scar on his forehead and the curse rebounded upon the evil wizard, who has been in hiding ever since." In the second book, Rowling establishes that Voldemort hates non-pure-blood wizards, despite being a half-blood himself.His worst fear is death." Throughout the series, Rowling establishes that Voldemort is so feared in the wizarding world that it is considered dangerous even to speak his name.Most characters in the novels refer to him as "You-Know-Who" or "He-Who-Must-Not-Be-Named" rather than say his name aloud.Harry defeats the manifestation of Riddle from the diary and the basilisk. Though it is initially implied that the prophecy refers to Sirius Black, the book's ostensible antagonist, the servant is eventually revealed to be Peter Pettigrew, who, for the 12 years since Voldemort's fall, has been disguised as Ron's pet rat, Scabbers.In Harry Potter and the Half-Blood Prince, Albus Dumbledore reveals to Harry that the diary was one of Voldemort's Horcruxes. In the fourth instalment of the series, Harry Potter and the Goblet of Fire, Voldemort appears at the start and the climax of the book.In a 2000 interview with the BBC, Rowling described Voldemort as a self-hating bully: "Well I think it is often the case that the biggest bullies take what they know to be their own defects, as they see it, and they put them right on someone else and then they try and destroy the other and that's what Voldemort does." In the same year, Rowling became more precise about Voldemort.