comics - Why was X-Men first produced?

What caused X-Men to be first produced, and why has it become such a huge success?

I realize today that the X-Men franchise is huge with large grossing movies, but I just want to know what kickstarted the franchise and why it has become one of the largest comic franchises known.

Answer

The X-Men were created because Stan Lee thought they would make a good superhero team. (Sorry, it's not much more complicated than that.)

Quote from Stan:

At the time, DC Comics had a book called The Justice League, about a group of superheroes, that was selling very well. So in 1961 we did The Fantastic Four. I tried to make the characters different in the sense that they had real emotions and problems. And it caught on. After that, Martin asked me to come up with some other superheroes. That's when I did the X-Men and The Hulk. And we stopped being a company that imitated.

If you're wondering "Why mutants?"

from another interview:

Then with the X-Men of course I figured everybody loved teenagers in stories in those days because they were the ones reading the books, and everybody was looking for a good group series because the Justice League was doing well and the Fantastic Four was doing well and they thought let's get another group. So I thought I'll get a group of teenagers and I'll give them each a super power. But by now I had run out of ways for characters to get super powers because I'm not very good at that. I mean I take the simplest, easiest way, the coward's way out. I had Spider-Man -- Peter Parker was bitten by a radioactive spider: That's easy. You can say that in one sentence. He became Spider-Man. He was bitten by a radioactive spider. The Hulk, Bruce Banner, was subjected to gamma rays. There was a gamma ray explosion. He got caught in it. I have no idea what a gamma ray is but it sounds pretty scientific, logical. Well, now I had already done radioactivity. I had already done a gamma ray. What am I gonna do next?

So I again, as I am tempted to do usually, prone to do, I took the cowardly way out. I said, "They're mutants. They were born that way. I don't have to explain anything. I don't have to worry about any more rays so that's it. A bunch of mutants get together." So when I finally wrote the thing and I brought it to Martin, my publisher, I wanted to call the book The Mutants. He said, "Stan" because he still didn't have much respect for the readers in those days. He said, "Nobody is gonna know what a mutant is. You can't call them the Mutants." So I went back and I thought for a while and the leader of the group was called Professor Xavier with an 'X,' and these were all a bunch of kids with extra powers so it occurred to me I'll call them the X-Men even though one was a girl but I hoped nobody would notice. So I said to him, "Okay. Instead of the Mutants we're gonna call them the X-Men," and I was amazed. He said, "Yeah, that's a good name," and I thought to myself as I left his office if nobody is gonna know what a Mutant is how is anybody gonna know what an X-Man is if he sees that on the cover?" But I had a name. I had won my battle. I didn't want to have any problems and you know, on and on. Then I did a lot of others and we were lucky and they sold and now I'm talking into a microphone for the whole world to listen. This is what happens when you write about monsters who have Jekyll and Hyde tendencies.

Why are they so popular?

Incidentally (or maybe not) one of the biggest reasons for the popularity of the X-Men, and other comics in the Marvel universe were exactly that the heroes had real emotions and real problems.

They also obviously spoke to the political climate of the day, tackling big issues like racism and prejudice. The very idea of a team fighting to protect those who hate and fear them makes them heroes in the noblest sense of the word.