In the 90s, DC's Who's Who series evolved into a loose-leaf format, and then merged with Secret Origins to become a series of one-shots that had both encyclopedic entries and a secret origin story... among other things. Let me do a blurb on the entire line before diving into the glory that is JLA Secret File #1.
Full title: (insert full title here)
Strengths: Full-length stories, "missing pages", and bonus features like faux magazine articles and posters, usually by the featured title's own creators.
Weaknesses: If you thought Who's Who didn't go into enough detail as to history and powers, Secret Files pairs them down even more.
That said, this is Grant Morrison's JLA, and he and his protégé Young Mark Millar (not to be confused with the current incarnation) are doing the honors. For the featured secret origin story, Morrison takes his cue from the original Justice League of America's first story which had them fighting Starro, a giant starfish from outer space. Starro's not in this one, but the alien enemy is starfish-shaped. When its ship appears in the middle of small-town Blue Valley, USA, the Flash responds to the threat with disastrous results:
These face-huggers would have us believe that we only use 10% of our brains because the other 90 was not our own to begin with. That's Grant Morrison for you, always scaring you shitless with trivia. In the wake of the United Nations having disbanded the awful Justice League of the time, the new "temporary" JLA will have to take care of it. Except the Spectre appears and shows them what happens if they do, and it's not pretty. They get taken over too, and then every hero falls the same way, followed by every planet in the DC universe. The plan, then, is to have the Spectre remove all of the JLA's powers, and they go in as mortals.
They're basically just a four-color diversion while Batman really saves the day, but you know what? In Morrison's JLA, it's often like that even when they DO have powers. He does it by figuring out that the alien ship's computer is networking the whole deal, sabotaging the air conditioning so that the temperature drops dramatically, turning the whole damn thing into a superconductor and short-circuiting it. The guy's just smarter than a starfish, y'know?
This story alone would be worth the price of admission, but there's more. "The Lost Pages" bring us two stories, the first being a fun enough exploration of the electric Superman's powers, the other showing 24 hours in the life of the Martian Manhunter. Wow, this is the real highlight for me. It presents the idea that our favorite shape-shifting Martian has many secret identities around the world, each with his "own habits, tastes and circle of friends." He considers them works of art in their own right. I wish this had been explored more in his own series, cuz it's a great, mind-blowing idea. I also love that he isn't attached to a single big city, but has rather made a name for himself in the parts of the world that don't really have super-heroes. He's a household name in Africa, Asia and Australia, more so than Superman! (It's true, cuz I didn't notice Clark Kent in the back of "Johann Johnson"'s cab until this very second.)
As for the encyclopedic entries, I was gonna say they're the weakest part of the comic, but that's not really true in JLA's case. The format is a bit thrifty, yes, with histories reading more like "story bibles" that tell writers why a character is part of the cast and what his or her personality is, while powers and abilities are simply pasted on top of the art in short, pithy phrases. But then I reread them, and it's pure gold.
Batman's described agenda is "to heal his city and hang up his cowl forever in the Batcave when the job is done. This is not a dream, but a plan." His relationship with Wonder Woman is strained "as is common when Royalty meets Wealth." I don't think I've ever read a Who's Who-style entry that actually gave us interesting characterization. Awesome.
And so we learn that the Flash "is at his most relaxed having ultrasonic conversations with other super-fast members," that the Martian Manhunter's accent is "deep and indescribable" and that "Green Lantern is his favorite." Aquaman is apparently a great storyteller, and Green Arrow was accused of nepotism by those who failed the membership drive. And there are a few villains in these pages too, such as the Lord of Time whose next attack "might take place tomorrow" or "on the warmest afternoon of your childhood". Excellent stuff, iconic in its poetry. Not all Secret Files are like this, but I'd say JLA's should be what they aim for.
Geek Moment: In a Playboy-style interview (not that I would ever read that for the articles), the Martian Manhunter mentions Gregory Reed as the actor playing him in a Martian Manhunter movie. Gregory Reed is the guy who played Superman in the pre-Crisis Hollywood! I'm glad to see he has a job in the new continuity! When I finally noticed this, it totally freaked me out.
Finally, the whole package is filled out by some kickass 2-page spreads by master of detail Phil Jimenez starring everyone that's ever even thought about becoming a member of the JLA, and a second one with all of the JLA's villains. That latter is the most impressive (127 characters), but the JLA's roster is probably more interesting to you:
95 characters are in there, including Power Girl's mangy cat, so it's safe to say it's fairly complete up to 1997. Just beautiful. You'll just have to track down the comic if you want the handy key that tells you who's who.