For decades, we have found comfort, even hope, in superheroes. Now they are the kings (and queens) of the box office. What explains their enduring appeal?

Over the years, superheroes have morphed to fit our social needs of the time. Whether it's "Iron Man," the biggest superhero star at the moment, or Superman, about to renew his brand with " Man of Steel," or "The Dark Knight," struggling to keep it together in Gotham City, we need superheroes to tackle problems that are too tough for mere mortals to handle.

"We look at Batman as being the ultimate policeman and Superman as the ultimate fireman," said Dan DiDio, the co-publisher for DC Entertainment, the comic book company that owns both franchises. "Superman is there to help people and save people. He is not passing judgment. He is not trying to push an agenda. When there are people in need, he is going to be there to help, no matter who they are."

Superheroes are the Greek gods of secular modern life - otherworldly figures able to tackle the problems of this human world. Like the gods of Greek mythology, they can be flawed. In fact, some argue that we need them to be flawed. Part of their appeal is that we can relate to them, despite their being superhuman.

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Hans Zimmer, who scored the music for "The Dark Knight" trilogy and the new Superman movie, "Man of Steel," said that while working on the Wagnerian theme music for Batman, the variation of a single note could signal hope, fear or vulnerability."

"I'm playing some sort of musical chess," Zimmer said, noting that as the final installment of the Christopher Nolan trilogy began when Batman was wounded.

The superheroes themselves have changed their metaphorical tunes ever so slightly over the years in response to the challenges we need them to tackle throughout history.

Superman first arrived from the planet Krypton in the 1930s during the gathering storm before World War II. In the cartoons of those early days, he fought Nazis and avenged the attack on Pearl Harbor.

In some ways, Superman was a Jewish superhero. Jerry Siegel and Joe Schuster, the two men who created Superman, were Jews, according to former DC Comics editor and comics teacher Jim Higgins, who teaches the Creating Comics class at the Los Angeles-based Meltdown Comics shop.

He called Superman "a metaphor for the Jewish immigrant experience."

"He's a strange visitor from another place," Higgins said. "He's a stranger in a strange land. He has to adapt to being there. He has to learn all the ways to be an American, the same way they did. You come to America, it's the land of opportunity, so you can become anything, even Superman."

Later, Vietnam and Watergate made us more cynical. Straight-arrow do-gooders suddenly seemed dated. That may explain why the Batman of the 1960s wouldn't dare take this superhero stuff too seriously. The '60s TV show was pure camp, an ironic take on the genre.

For die-hard fans in those years, admitting you like men in tights became about as cool as attending a "Star Trek" convention.

"For a long time, comics has this air of disrespectability," Higgins said.

That changed on Sept. 11, 2001, with the attack on the World Trade Center and the Pentagon. The world was once again divided into good and evil, but was still morally complicated, flawed and vulnerable.

Suddenly, superheroes came back in a big way.

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Captain America, a Marvel Comics character that originally debuted in the 1940s shortly after Superman, made a reemergence in the 2000s and the 2011 film, "Captain America: The First Avenger," took on the 9/11 attacks.

"To see Captain America standing at Ground Zero, sort of being, not like Batman - 'Rah, we'll get 'em' - no," Higgins said. "It was like he was there helping get people out of the debris and all that stuff, and then it was sort of the mourning period with Captain America, and Captain America was sort of like, 'Let's hold it all together.'"

The 2008 economic collapse doubled down on the chaos and uncertainty so that by the time "The Dark Knight Rises" was released in 2012, the story told of a troubled billionaire in a bat costume battling a villain who might as well be from Occupy Wall Street.

Who do you root for in that scenario?

Credit: Credit: Ron Phillips/Warner Bros. Pictures.

Times have changed not only in terms of the challenges the new Superman faces in "Man of Steel," set to premiere on June 14, but also his day job.

"Clark Kent is actually a blogger at this moment in time," DC's DiDio said. "He left the Daily Planet and is really going to establish himself in a way that makes him feel like he's in touch with the world today. He's a digital journalist."

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Batman has moved on, too. Adam West, who starred as the classic Batman of the '60s, is now the voice of Mayor West on TV's "Family Guy." To most folks, however, he will always be the Caped Crusader.

In fact, he said he spent years trying to escape being a superhero.

"Because I was typecast extraordinarily," West said. "It was difficult, but after five years of doing dumb films, I decided that people love Batman, so why the hell shouldn't I love Batman? Why be an ingrate? So I became rather fascinated by it and how to keep that particular culture thing going."

West has found that superheroes never grow old. They just change with the times.