Lord Voldemort performer Ralph Fiennes
In Harry Potter and the Goblet of Fire, Voldemort is initially only heard, possessing the scratchy, weak voice heard in the first film. By the film's climax, however, he appears in his physical form for the first time, played by Ralph Fiennes. As in the book, Voldemort is shown clad in dark black robes, being tall and emaciated, with no hair and yellowish teeth; his wand has a white tone and the handle appears to be made of bone; his finger nails are long and pale blue while his toe nails appear to be infected. Unlike in the book, his pupils are not cat-like and his eyes are blue, because producer David Heyman felt that his evil would not be able to be seen and would not fill the audience with fear (his eyes do briefly take on a snake-like appearance when he opens them after turning human, but quickly turn normal). As in the book, the film version of Voldemort has snake-like slit nostrils with the flesh of his nose significantly pressed back. Ralph Fiennes' nose was not covered in makeup on the set, but was digitally removed in post-production. In this first appearance, Voldemort also has a forked tongue, but this element was removed for the subsequent films.
Fiennes stated that he had two weeks to shoot the climactic showdown scene where he is gloating over a terrified Harry, played by Daniel Radcliffe. Fiennes said with a chuckle: "I have no doubt children will be afraid of me now if they weren't before." In preparation, he read the novel Goblet of Fire, but jokingly conceded: "I was only interested in my scene, and I had to go through thousands and thousands of other scenes which I did, dutifully, until I got to my scene and I read it many, many, many, many, many times and that was my research." Fiennes reprised his role as Voldemort in Harry Potter and the Order of the Phoenix and Harry Potter and the Deathly Hallows – Part 1 and Part 2.
Fiennes's nephew, Hero Fiennes Tiffin, portrayed Tom Riddle as a child in Harry Potter and the Half-Blood Prince. By the time filming arrived Christian Coulson was 29, and not considered suitable to return as the adolescent Riddle. Thomas James Longley was originally scheduled to take over the role, but last minute renegotiations saw Frank Dillane cast instead.