The Phantom of the Opera

The movie starts with an auction being held in the Paris Opera House. The Opera has been shut down and they are auctioning off props to make some money. One of the items is a stuffed monkey dressed in Persian robes and playing the cymbals sitting on top of a music box. An older gentleman in a wheelchair buys the monkey and holds on to it tightly. The next item is a chandelier that was broken but has been repaired. When the chandelier is revealed, we are whisked back to 1870 ("Overture") where we see the opera house in full swing for it's performance of Hannibal by Chalemau. Rehearsals are under way when the Opera manager informs the cast and crew that he is leaving for Australia and that the Opera House is now under the command of Gilles Andre and Richard Firmin (Simon Callow and Cirian Hinds).When they resume rehearsal, a stage prop falls on the lead diva, Carlotta (Minnie Driver). After she storms out refusing to sing, Madame Giry (Miranda Richardson), the ballet instructor, convinces the new owners to let Christine Daaé (Emmy Rossum), one of the dancers, to take Carlotta's part. After a stunning performance ("Think of Me"), Christine goes down to the small chapel under the Opera House to pray for her father who died long ago. Meg (Jennifer Ellison) one of the ballet dancers and Christine's best friend comes to find her inquiring of her singing prowess ("Angel of Music").Later, Christine's childhood friend Raoul, the Vicomte de Changy and patron of the Opera House, comes to visit her in her dressing room. He had been in the audience and had recognized her. After inviting her to a party and leaving to prepare for the ride, Christine is locked in her room and hears singing. The Phantom (Gerard Butler) is mad at Raoul for taking credit in his work in training Christine to sing. He then lures Christine to a mirror where she sees him then follows him to his lair under the Opera House ("The Phantom of the Opera"). Once there the Phantom expresses his feelings for Christine and tries to convince her to stay with him ("Music of the Night"). Later she unmasks him and the Phantom is furious with her. Although he is raging and angry, he becomes vunerable and begins crying. He wishes he didn't have a loathsome gargoyle face ("I Remember/Stranger Than You Dreamt It"). He then returns her to the surface.While Christine is gone, Andre and Firmin are upset because Christine has disappeared and they no longer have a lead to play in the operas. After receiving a series of notes all signed O.G. (Opera Ghost) they find out that Christine has returned and they have been instructed by the Phantom to put Christine in the lead role of the upcoming opera II Muto. They refuse and put Carlotta in the lead part after convincing her to return ("Prima Donna") and give Christine a silent role, which infuriates the Phantom. He then disables Carlotta's voice giving her the voice of a toad, which forces the Opera managers to put Christine in the lead role. While Christine is getting ready, Joseph Buquet (Kevin McNally) finds the Phantom in the rafters and after trying to escape is caught and hung from the rafters on stage in full view of everyone. This frightens Christine and she runs to the roof with Raoul pursuing her where he comforts her telling her that he loves her and will never leave her ("All I Ask of You") The Phantom overhears and is now in a state of shock because Christine loves Raoul and not him.3 months later, we see that the Opera House is in full swing without any appearance from the Phantom since he disabled Carlotta's voice. The Opera House is holding a Masquerade to celebrate ("Masquerade"). During the Masquerade the Phantom interrupts and presents the managers with a new Opera he has written called Don Juan. He then gives them an ultimatum. Follow his instructions or bad things will happen. Christine visits the graveyard where her father is buried ("Wishing You Were Somehow Here Again"). The Phantom is also there and tries to lure her to him but Raoul arrives and fights off the Phantom in a sword battle. They then leave the Phantom there and he swears to get revenge.The performance of Don Juan has finally come and everyone is nervous. Raoul, Andre, and Firmin are positive the Phantom will make an appearance so they set a trap. Christine is torn. She explains that she can't be a part of the trap without the Phantom taking her back. The play starts and Christine comes on stage singing. Backstage, Piangi (Victor McGuire) is getting ready for his next scene when the Phantom kills him and takes his place on stage. Christine sings with the Phantom, expressing her love for him. Raoul, who is in the audience, sadly realizes that Christine loves the Phantom ("The Point of No Return"). The Phantom then sings passionately to Christine who takes his mask off, revealing to the audience the distortion of his face. He takes her once again down to his lair, causing the opera theatre to catch on fire in the progress after bringing down the chandelier ("Down Once More/Track Down This Murderer"). The Phantom gives Christine the ring that he took from her at the masquerade ball, and asks her to stay with him. Meanwhile, Raoul gets Madame Giry to take him to the Phantom's lair. She leaves Raoul halfway through their journey, and Raoul goes the rest of the way alone. After nearly drowning, he shows up in the Phantom's lair to save Christine. The Phantom then gives Christine the difficult desicion: she can either stay with the Phantom and Raoul (who has been tied up by the Phantom) goes free, or she refuses the Phantom and Raoul dies but Christine goes free. Christine decides to stay with the Phantom and tells him that he is not alone. She kisses him passionately. At this the Phantom realizes that Christine truly loves him, but his horrible actions have ruined any chance they have together. In an act of selflessness, he frees both Christine and Raoul. Christine gives the ring back to the Phantom who sadly tells Christine that he loves her. Christine forces herself to leave with Raoul in the boat. She looks back at the Phantom sadly, knowing that she loves him. Heartbroken, the Phantom destroys the mirrors and escapes through a secret passage just before the mob shows up. Meg Giry finds only his mask.The scene then switches back to 1919. The elderly gentleman now known to be Raoul leaves the monkey music box on Christine's grave. He looks down and sees that the Phantom has left a rose tied with a black ribbon (his trademark) and the ring that he gave to Christine: the Phantom still loves her. Raoul sadly looks at it knowing that Christine truly loved the Phantom.

Question: Who does the Phantom kill and take the place of during the performance of Don Juan?
Answer: Piangi