It was a known fact that almost everybody in the wizarding world feared Lord Voldemort and never called him out or spoke of him by name. Most people just called him He-Who-Must-Not-Be-Named or You-Know-Who. His Death Eaters referred to him as the Dark Lord. However, there were some people who called him by his name. Albus Dumbledore had always called him Tom Riddle and continued to do so. When he spoke of him, he referred to him as Voldemort. Harry too called Voldemort Tom and when he spoke of him, he called him Voldemort. In the movie adaptations, Hermione eventually began calling him Voldemort and so did Professor McGonagall and a lot of other people.