JLA/Avengers by Kurt Busiek and George Pérez
Everybody loves a good team-up. No matter who your favorite hero is, whether in the realm of sports, music, science, writing, art - you get a secret thrill from the idea of what they could achieve if they worked together. Sometimes it's brilliant, like when Neil Gaiman and Terry Pratchett teamed up to do Good Omens. Sometimes it's inspiring, like the pop music wonder that was "We Are the World." Sometimes it's overwhelming, like the 1992 Olympic basketball Dream Team. Sometimes it's Damn Yankees, and the less said about that, the better.
Regardless, we all love to play that game of "What if," pairing together not only the greatest talents we know, but sometimes the greatest talents in history. What if Albert Einstein and Isaac Newton could have studied the universe together? What if we could get Abraham Lincoln, Franklin Roosevelt and John F. Kennedy together to work on the problems facing the nation? What if Kurt Kobain and Jimi Hendrix were able to cut an album together? The team-ups are endless, and most of the time they're impossible.
Fortunately, that's where fiction steps in. The Justice League was created by Gardner Fox and Mike Sekowsky over at DC Comics back in 1960. The idea was to take the greatest heroes the company had in their library and team them up to fight battles that no one hero could face alone - Starro the Conquerer being the first among them, and thereafter many more. Aliens, mad scientists, evil kings, vengeful gods, all those who attempted to conquer, destroy, or devour the Earth were stopped by the League. Though the membership roster has changed many times over the years, as has the style of the books, the League has been a fixture in the DC Comics universe for more than forty years.
As Stan Lee tells the story, the publisher of DC Comics, Jack Liebowitz, bragged over a round of golf to the owner of Marvel, Martin Goodman, about how well his new Justice League title was selling. After the game, Goodman called Lee and told him to create a hero team to compete. Stan's imagination provided him with the Fantastic Four, and a comic book arms race had begun. Lee produced hero after hero for Marvel, conveniently housing most of them in New York City. From there, it made sense to have them get together to fight even greater menaces. With the pencils of comic book legend Jack Kirby, Lee created The Avengers, the mightiest hero team of the Marvel universe. They too have undergone a lot of changes in the last four decades, but they remain the elite team of heroes to which every costumed adventurer aspires.
Superman, Batman, Aquaman, Wonder Woman, Green Lantern, Flash, Martian Manhunter....
Captain America, Thor, Iron Man, Ant-Man, Hulk , the Wasp, Hawkeye....
These are names that every comic book fan should know, and deep down inside we all wonder: what would it be like if they could get together? What's more, what kind of foe would require the combined might of two of the greatest hero teams in comic book history? It could only be something on a monumental scale, something that endangers the existences of both universes. Something like... Krona.
If you're a long-time reader, you might remember that name. Krona was the reason for the Crisis on Infinite Earths - his obsession with seeing the beginning of the universe led to the fissioning of that universe into a nigh-infinite number of parallel ones. It was only after a titanic series of battles that the singular universe was put right, and Krona was transformed into pure energy and banished for his crimes. Or so we thought.
Obsessive to the core, Krona figured out how to escape his universe and started again on his quest to understand the beginning of all things, even if it meant destroying every single universe that defied him. Eventually he came to meet the Grandmaster, an immortal on the Marvel side whose limitless existence drove him to play cosmic games of chance with whatever other great powers he encountered. He knew someone who could possibly answer Krona's questions - the planet-devourer Galactus - and challenged him to a contest: the greatest heroes of each universe would compete to gather items of power. If the DC team won, Krona would leave and search elsewhere. If Marvel's team won, it would bring ultimate destruction to both cosmoses.
And so the teams met, and like all good superhero team-ups, it started with a fight. Something about the two worlds put the visitors on edge, and both Superman and Captain America were willing to pound their opposite numbers into the dirt if need be. Fortunately, as in all good hero team-ups, their differences were put aside in favor of battling Krona and saving both of their universes from utter annihilation.
It's a vast story, both in time and space, and manages to bring together pretty much everyone who has ever been part of the two teams, both in terms of the heroes that made them up and the villains they fought. Yet it feels fairly intimate - these aren't two whole universes that are battling for survival, but two teams, who manage to mesh together surprisingly well. A lot of the credit for this, of course, has to go to the writer, Kurt Busiek, who had the unenviable task of penning a story that made the best - and fairest - use of both teams. After all, never underestimate the partisan fans, the ones who would be utterly incensed by Superman beating Thor, or the idea that Captain America could possibly be Batman's equal in hand-to-hand combat. I'm sure there were people on both sides of the publishing divide who were keeping very careful account of which team came off "better" in this fight, but that's not the way this book was meant to be read. Busiek's mission was to create a threat that could only be contained by both teams together, which means that neither team by itself was enough to win, which means that you should shut up already about whether or not Superman should have been able to use Thor's hammer, dammit.
Even for all the care that went into writing this story, it never would have worked without an artist capable of handling that many characters and making sure they all looked their best. When you have a universe-spanning epic with a cast of far-too-many, there's only one person you can call: George Pérez. Not only can he handle a chaotic battle scene, making every hero look... well... heroic, hes just as good at the casualness of a Christmas party, or the masks-off teamwork that is involved in trying to build a reality-piercing spaceship. Whether facing off against great cosmic powers or chatting next to the coffee urn, Pérez knows how to make these people look damn good. There's just no one else like him. With outstanding colors by Tom Smith, I could just read this book for the artwork alone.
What I also found interesting was a look at how the two worlds are fundamentally different in not only their stories but their very makeup. The Flash can't run in the Marvel Universe because the Speed Force doesn't exist, while the Scarlet Witch's powers are multiplied to dangerous levels in the DC Universe thanks to the strength of the Lords of Chaos. The differences in the geography and the sizes of the Earths, the type of energy they receive from their suns, the fundamental forces that hold their universes together are a huge obstacle to getting the teams to work together, and as far as I know it is the first attempt to "scientifically" delineate how they are different.
There is also a bit of sociological analysis, too. Each team first notices how differently heroes are treated in their opposite worlds. The heroes of the Marvel Universe are tolerated, but not entirely trusted. The non-powered citizenry tend to be more afraid of superheroes, especially the mutants, and so the ability of groups like the Avengers to effect positive change on their world is limited. To Superman, this looks like Marvel's heroes aren't bothering to make their world better, but only remaining satisfied to hold the status quo.
On the DC side, heroes are beloved. Superman is a planet-wide hero, Wonder Woman is an ambassador of peace, and the people of Central City have built an entire museum to honor the Flash. These people revere their heroes as both celebrities and saviors, something that Captain America views as a step towards fascism - costumed gods with their pet people ready to do what they say.
Neither viewpoint is entirely right, but they do reflect a fundamental difference in the way each company approaches its storytelling. To put that editorial decision in front of the characters was an interesting choice, and allowing them to come to their own judgments was fun - if a little unnerving - to read.
All in all, JLA/Avengers is a truly great team-up story, one that should make the fans on both sides happy for a while.
"Neural chaff. Hypnotic lights. Pre-programmed skills. Try fighting the Wehrmacht, mister - it teaches you focus!"
Captain America to Prometheus, JLA/Avengers
 Hulk gets almost no screen time in the story, which is very disappointing. I'm sure there are reasons for this....