They say that imitation is the highest form of flattery, a principle Hollywood has most certainly taken to heart. In the 1960s, major hits in the musical genre, like My Fair Lady and The Sound of Music, led to a string of lesser knockoff musicals, most of which were expensive disasters like Doctor Dolittle or Camelot. More recently, the commercial and critical success of Gladiator led to a string of mediocre sword-and-sandals epics, from Troy to Alexander. The problem isn't just Hollywood's propensity toward copying success; it's that they tend to be so bad at it.The latest trend is the superhero genre, which has quickly become Hollywood's most consistent big moneymaker. While it may feel like Hollywood has only recently begun mining comic books for material, the genre dates back to 1978's Richard Donner-directed hit, Superman. Though the one-two punch of Superman 2 and Tim Burton's Batman would both be enormous successes for Hollywood in the 80s, the string of sequels and knockoffs would prove more than disappointing. Superman 3 and 4 are surely among the worst movies you have never seen, and though Batman Returns was a solid sequel, the Joel Schumacher-directed Batman and Robin and Batman Forever proved embarrassing for the franchise. If that weren't enough, a string of attempts to copy Batman and Superman's early successes were mostly failures, including long forgotten films like Supergirl and The Punisher. By the end of the '90s, it seemed as if the superhero genre had died out before it had ever gotten its chance to truly shine.

But a funny thing happened at the turn of the century, when Hollywood began to realize that DC Comics superheroes weren't the only big name in town. Though a Marvel Comics character would make his big screen debut in 1997's critically appreciated though quickly forgotten Spawn, the arrival of X-Men in 2000 would mark a major shift for the superhero genre. Not only did the film's great commercial success (nearly $300 million worldwide) almost single-handedly revitalize the genre, but the fact that a critically acclaimed director like Bryan Singer (The Usual Suspects, Apt Pupil) would take on a comic book franchise helped lead the way for other successful directors to follow. From Sam Raimi doing the Spiderman series to Ang Lee taking on The Hulk, and finally to Guillermo Del Toro manning Hellboy I and II, it has become perfectly acceptable for a critically acclaimed, even Oscar-nominated director to take on a big-budget Hollywood superhero film.

This of course brings us to this summer, when superhero films undoubtedly ruled the box office arena. The two highest grossing movies of the year so far have been The Dark Knight and Iron Man, with a number of other superhero films, including Hancock, The Incredible Hulk and Hellboy II doing strong business as well. If that weren't enough, The Dark Knight and Iron Man are also two of the most critically acclaimed films of the year, managing the difficult combination of being both box office hits and critically beloved, with The Dark Knight even being mentioned as a possible Oscar contender. The superhero genre is as strong as it has ever been, and with new additions to the X-Men, Spiderman and Iron Man franchises all reportedly on the way, it seems like things are going to continue to be good for the superhero film.

And yet I can't help but feel as if this summer in some way represents a high mark for the superhero film. Throughout Hollywood's history, genres seem to find their creative and commercial apex and then begin their slow decline as audiences, followed by Hollywood, move on to newer, more profitable genres. It happened to the Western and the musical, and it will inevitably happen to the superhero film. So why do I think now is that critical moment, that tipping point at which the superhero will begin to fall? Mainly because, well, it doesn't get any better than this. There have always been two types of superhero films, the first being the Superman and Spiderman type, in which action and romance rule the day and there is hardly a serious thought in the film. These types of films are designed from the bottom up to be blockbusters, bringing in crowds by the thousands and delighting everyone in the family. Of these types of films, there has perhaps never been one better executed than this summer's Iron Man. Boasting a tremendous performance by Robert Downey, Jr., and a tight script, Iron Man is everything one could want from a superhero blockbuster. It provides laughs, action and even a bit of romance, and perhaps most importantly, there are absolutely no serious or controversial themes to the movie. The film seems to go out of its way to make sure there is little complexity, and when Iron Man stomps across Afghanistan killing terrorists, we can't help but delight in the escapist pleasure of it all.

The second type of superhero film has been the darker, slightly more serious type of sort film, highlighted by the X-Men series with its themes of intolerance toward the outsiders of society. If the first type of superhero film reached its apex with this summer's Iron Man, surely no superhero film will be able to outdo The Dark Knight and its combination of big action thrills with a legitimately thoughtful script. If The Dark Knight has its fair share of explosions and car chases, the film seems far more interested in exploring themes like the role of anarchy and chaos in the modern world. Interestingly, the villain of the film, the Joker, ends up feeling like more of a real world terrorist than any of the so-called terrorists seen in Iron Man. Finally, while many have written about the sheer terror of Heath Ledger's Joker, the scariest aspect of the film for me was that the film seems to actually identify as much with his character as it does with Batman's. One scene near the end of the film is telling, as a dangling upside-down Joker slowly is turned right-side-up within the frame, and the audience is left mesmerized as traditional moral values are literally turned upside down. Perhaps the most interesting thing about The Dark Knight is that it was even made at all. It was not long ago that no studio would have even considered giving hundreds of millions of dollars toward making such a subversive film.

So, with Iron Man and The Dark Knight gaining critical raves and huge audiences worldwide, I am left with one question: where does the superhero genre possibly go from here? While Dark Knight sequel is inevitable given its huge box office earnings, there seems little chance the writing team will come up with a storyline so gripping nor a villain so compelling as in The Dark Knight. Even comparing the ending of this film to the ending of its predecessor, Batman Begins, it seems obvious that the writers have less of a clear direction than they did before. While Batman Begins ends with a foreshadowing of the introduction of the Joker character, The Dark Knight ends in a way that leaves little room for a sequel, especially given the tragic death of the young, immensely talented Australian Heath Ledger.

Likewise, while the inevitable Iron Man sequel will surely deliver loads of entertainment, it seems almost a foregone conclusion that the series will devolve into the mediocre sequels that seem to come inevitably in any comic book franchise, be it Superman 3 & 4, Spiderman 3, or X-Men: The Last Stand. Despite the fact that each of these franchises started strong, by the third installment the creative juices had run out, and instead of the focused characters and stories of the originals, audiences were given a muddled glut of action and adventure. If the predictable disappointment of the sequels to Iron Man and The Dark Knight weren't enough, the unavoidable endless stream of Hollywood knockoffs will surely help the genre's slow demise along. Though Iron Man and The Dark Knight undoubtedly mark a high point for the superhero genre, they just may mark the beginning of the end, too.