Erik is the name that the phantom of the Opera has taken for himself; his real name is never revealed in the book. He was born deformed, and it was his mother, whom Eric refers to several times, who gave him his first mask. He was born in a little town near Rouen but ran away as a young man, sometimes exhibiting his gruesome looks at country fairs under the title of the living dead man. As a performer, he learned to become proficient as a musician, a magician, and as a ventriloquist. Summoned by a shah to Persia, he designed a palace with hidden panels and trap doors. The shah ordered him executed, to keep the palace's secrets unknown, but the Persian helped Erik escape.
In Paris, Erik was part of the construction team that helped Charles Garnier build the Paris opera house. Because he knows where the secret passageways are, he is able to move about the opera house without being seen. Because he is proficient in ventriloquism, he is able to speak from hidden places and to make people think that his voice is coming from the empty air beside them. And he uses his musical skill to compose a masterful violin opus, Don Juan Triumphant, which he has worked on for decades in his home in the opera house's cellars.
As the phantom, Erik demands that the managers of the opera give him an annual stipend and a private box. Erik falls in love with Christine when he meets her. For a while, he pretends to be the Spirit of Music that her father once told her about, and he trains her to become a great singer. When he is unable to make her love him, though, he becomes insane. He kidnaps her and eventually threatens to blow up a quarter of the town with all of the gunpowder he has hidden beneath the opera house. In the end, though, his heart is softened by her promise to love him, and he lets Christine and Raoul go free to marry each other. When he last appears in the novel, it is to tell the Persian that he is dying of a broken heart.
The mother of the girl known as Little Meg, Mme. Giry is also the attendant of Box Number 5, which is reserved for the phantom. She has never seen him, but she does services for him, like bringing a program and a footstool to the box. In return, he leaves her tips and gifts. When she is fired by the opera's directors, a huge chandelier falls on the audience, killing just one person: the woman hired to replace Mme. Giry. She is assigned to deliver money to the phantom, and when the money in the envelope is changed for counterfeit money, the directors threaten to turn her over to the police until they find out that she could not possibly have stolen it. They do find out why she is so interested in helping the phantom; in addition to the tips that he gives her, he has predicted that Little Meg will be the empress by 1885.
One of the opera's featured dancers, La Sorelli is a diva who expects to be the center of attention. When she dances, the narrator explains, "she appears to be in a tableau so lascivious that it could drive a man to blow his brains out." But she is also presented as a vain, stubborn woman.
Monsieur Lachenal is the stable master of the opera house, in charge of the horses that are trained to perform in operas.
One of the new directors of the opera, Moncharmin has no musical training but is rich and socially connected. His working relationship with M. Richard is threatened when the phantom is able to steal an envelope of money from Richard's pocket. The book's narrator relies on Moncharmin's autobiography, The Memoirs of a Director, as a primary source for the events reported in the book.
The Persian is a witness of the events at the opera house, whom the narrator interviews about what happened to Raoul de Chegny and Christine Daaé. The Persian is so famous that he cannot be referred to by his real name. He is a shadowy figure throughout much of the story, until the final chapters. Then, it turns out that he has known Erik, the phantom, for years, from the time when he was the daroga, or chief of the national police. In Persia, he saved Erik from execution and lost his government position because of it. He knows many of the secrets of the phantom's underground world, having followed him and observed him and once having nearly been killed by one of his traps in the underground lake.
When Christine is kidnapped, the Persian steps forward to help Raoul find his way through the underground world to the place where she may have been taken. In the course of the rescue mission, his advice is invaluable, but he nearly loses his life when the cellar he is in is flooded. The phantom saves him, though, and, after making sure he is all right, knocks him out with drugs and deposits him in a doorway.
With Monsieur Debienne, Monsieur Poligny is one of the directors of the Paris Opera who is retiring in the opening chapters of the novel.
One of the opera's new directors, Richard is an accomplished musician and composer. He is characterized as loving all types of music and all musicians. He is skeptical of the existence of the phantom and hesitates about giving in to his demands. When the money disappears from an envelope that is pinned in his pocket, he and his partner, M. Moncharmin, become suspicious of each other, a suspicion that seems, according to Moncharmin's memoirs, to last throughout their professional relationship.
Madame Maudie Valerius
Christine is staying at the house of Mme. Valerius, an old friend of her father. Raoul de Chagny goes to the house when Christine disappears the first time, but Mme. Valerius cannot tell him where she is. She is convinced that Christine has gone away with the Spirit of Music.