It's a summer for heroes.

Sitting serenely atop Box Office Mojo's 2008 rankings at the end of last week were Iron Man and Indiana Jones and the Kingdom of the Crystal Skull, each with revenue of more than $310 million in North America alone.

Superhero comedy-drama Hancock was in fourth place, with $171 million and counting. The Incredible Hulk was in ninth ($130 million-plus).

And there's no doubt that The Dark Knight, the latest Batman film, will climb quickly into the upper box-office echelon. Shows were selling out in advance, and Deadline Hollywood Daily estimated that it will make $130 million just in this, its opening weekend.

But it's not just on the big screen that we're awash in heroics. TNT has begun new episodes of its crime-fighting twosome of The Closer and Saving Grace.

And even shows that are not devoted to battling evil are thinking about heroism. In a new episode of Mad Men, the Emmy-nominated series beginning its second season on July 27, two ad men in 1962 New York discuss a ticker-tape parade for astronaut (and Buckeye) John Glenn.

''Incredible what passes for heroism these days,'' says one. ''I'd like ticker tape for pulling out of my driveway and going around the block three times.''

But that man is not alone in pondering what qualifies as heroism. The shows and movies mentioned above are not for the most part about white hats.

Instead, they believe heroes have to show human failings before they become heroes, or carry deep flaws into their attempts to do good.

Indiana Jones, though roguish, is the closest thing to an old-fashioned hero in movies right now — and he had to face advancing age. The end of Crystal Skull hints that further adventures could focus on Indy's more rebellious son.

But more common are severely flawed heroes. Consider Grace Hanadarko, the smoking-and-drinking-and-whatever police detective played by Holly Hunter on Saving Grace. Or Tony Stark, the dissolute billionaire who becomes Iron Man, played by Robert Downey Jr. with an aura of the hard living the real-life Downey had done.

The Dark Knight's nominal hero, Batman (Christian Bale), is an outlaw in his own city; the movie's title echoes when the new district attorney, Harvey Dent (Aaron Eckhart), is referred to as a white knight. And when Batman and Dent battle the Joker (Heath Ledger), the battle includes debates about how far one must go to combat evil, and where the line is between good and bad.

Will Smith's Hancock, meanwhile, at first appears as a homeless, insulting, reckless, nasty man who happens to have superpowers. From the beginning, the movie asks us to consider whether great power is simply an arbitrary gift or something that has to be earned.

NBC's Heroes series repeatedly looks at the issue of what should be done with extraordinary abilities; although the show's title is Heroes, some of its powerful people embrace villainy, or suffer personal torment while trying to deal with their gifts.

Now, flawed heroes have been part of the popular culture for a long time. Comic books, the breeding ground for many big-screen heroes, have had unhappy heroes for decades, through the pioneering angst in Marvel Comics and the complexities of the more adult form, the graphic novel.

Even at the movies, the possibility of a sullen hero has long been around; the iconic hero John Wayne played complex, even unlikable, figures in movies like The Searchers, Sands of Iwo Jima and Red River.

But why so many now? I suspect that the world has become too complicated for anyone to accept a contemporary hero who is pure of heart — or that even the purest hero can accomplish much.

We live in a culture where politics and tabloid news consider anything and anyone suitable for trashing. In 2004, John Kerry thought he could campaign as a war hero — until the Swift Boaters made a seeming benefit into a liability.

This year, retired Gen. Wesley Clark sounded like that Mad Men ad man when, after praising John McCain's heroism as a prisoner of war, he added that ''I don't think riding in a fighter plane and getting shot down is a qualification to be president.''

For entertainment purposes, it may be better to give a hero flaws up front, so that we can consider the good deeds without sanctifying the deed-doer. Then a damaged hero suggests that, just as noble intentions cannot overcome personal limitations, so there may be problems in the world that even great skills and nobility cannot overcome.

The war in Iraq and the sour economy by themselves seem to be more than one person can handle. That's certainly the notion underlying another tale of heroes, the Iraq-war miniseries Generation Kill. The young Marines in the drama are for the most part very able in battle. They are also hampered by military (and government) politics whose goals can be contradictory and self-defeating; the Marines' vulgarity and insensitivity seem to reflect the disorder and cynicism of the system in which they have to operate.

The current heroes operate in a world full of limitations, some of them of their own making.

Brenda Johnson, the brilliant investigator and interrogator played by Kyra Sedgwick on The Closer, can solve a tricky crime. But she cannot stop all criminals. (Last week's episode had one bad guy caught, and another still on the loose.) Nor does her detecting skill make her any better at dealing with problems at home.

Tony Stark, for that matter, has all the powers of an Iron Man suit — but carries the weight of his past and personal weakness in it. And Batman? As the movie says, he is a dark knight.

Rich Heldenfels writes about popular culture for the Beacon Journal and in the HeldenFiles Online blog at http://www.ohio.com. He can be reached at 330-996-3582 and rheldenfels@thebeaconjournal.com.