How did the Phantom look like that?

Question

In The Phantom of the Opera, the phantom (according to the 1923, 1925, and 1987 animated version) has a skull-like face. I was always wondering how his face got to be like that?

Answer 1

Birth defect apparently

"Facially deformed since birth, the Phantom is a genius composer and musician who hides behind a white mask and is known to the managers and actors as the "Opera Ghost".

but in the 1943 movie version, they changed it:

"Phantom of the Opera is not a remake of the 1925 version or based off the book. The story goes a different route. In this version, an aging musician is fired from his job as the Opera House violinist and goes to a publisher to have his concerto published. When he catches the publisher trying to steal it, he attacks him, so the publisher's assistant throws acid in the musicians face. He ends up living under the Paris Opera House and demanding that back up singer Christine Dubois be given larger roles. As he begins to murder people and destroy the Opera House, two of Christine's suitors set out to stop the phantom once and for all. This isn't the best version of the story, but it's the version I grew up with, so it is one of my favourite versions of the story.
The new version of the story is very good with an interesting new origin for the phantom. This is the first version I saw, so the birth defect origin from the book and original film were a little weird to me. I always thought this version was vastly entertaining."

in Andrew Webber's version they went back to the original birth defect:

"Evil is of course, defective, but it is not his fault, he was born that way and mistreated until he snapped. His outrage at mistreatment, his hatred of the world above is understandable and forgivable. Not a critical character fault, but a birth defect. His ugliness, his face is repulsive but people's response to it explains and excuses the stain of evil on his soul. His genius, his musical talent, his moody and provocative music is the good result of his brooding on evil and his alienation from the rest of mankind. It is not that evil chooses to wallow in sin, but that sin is unjustifiably forced on a young boy who just responses as we all would. He is excused."

Answer 2

exactly as the above user said, it depends on what version. In some versions and books he was born with it...in some acid was thrown on his face, his face was burned by fire or he was 'cursed by the devil' who said that people would love him only for his music. i know there are diseases out there that do strange things to the body and skin, like his yellowish color could have been a disease, his sunken eyes also. but he was such a beautiful man on the inside. he was only hateful because others treated him with hate because he looked different than them.
despite his deformities Erik was an amazing man.