Batman: The Dark Knight Strikes Again, also known as Dark Knight 2, was a three issue Batman mini-series written and illustrated by Frank Miller with Lynn Varley in 2001-2002, the sequel to 1986's The Dark Knight Returns.Set three years after the events of The Dark Knight Returns, the world has managed to go downhill since then- the President is a fake, and the police state of a world is run by Lex Luthor and Brainiac, who has many a hero enslaved.Of course, Batman won't be having that, so he and his allies—Catgirl, the Green Arrow, and his Batboys—set out to change the world by judicious application of violence. But first, they need allies—and they need to deal with Superman, who is still in the thrall of the government...Overall it goes further off the deep end than The Dark Knight Returns, almost to the point of being a Deconstruction of the Darker and Edgier nature of the first story though, naturally, not everyone thinks that makes it any good. The color palette is much more varied than The Dark Knight Returns' muted colorization, taking it to an almost garish degree, that takes a little getting used to (many reviewers termed it ugly).
The art in general is also very different from the first book. The coloring is the most obvious change (from muted and dirty to garishly bright) but everybody has really exaggerated figures either in terms of proportions or angles. Lex in particular looks like a shaved gorilla.
Author Tract: Apparently Miller doesn't like trends the media are taking.
Badass Grandpa: The majority of the superheroes are really really old in this book. They can still kick the crap out of you and each other.
Invincible Hero: Batman. By the time anyone comes up with anything he's already twelve steps ahead of them. Superman heading for the Bat-Cave? No problem! Just use the the gigantic Kryptonite gloves over there! Got captured? No biggie! It was part of Batman's plan all along. It gets so bad that Batman can literally storm into Luthor's base of operations, beat him up, cut his face, and just leave with absolutely zero consequences. In the page image, he spells out why — he wanted to inspire terror in Luthor, to let him know that his empire was crumbling. And he wanted to give Hawkboy the honor of killing Luthor.
Butt Monkey: Superman. It really gets to the point where you think Miller has something against the character.
Depraved Homosexual: it's implied that Dick Grayson had the hots for Batman, but was rejected by him, which led to Dick becoming a villain. At the end of the comic Batman taunts him with all sorts of quasi-homophobic euphemisms relating to his supposed "sissiness". And since Dick is the villain, apparently Miller thinks we're supposed to side with Batman here.
Destructo-Nookie: Superman and Wonder Woman have sex so over-the-top it alters the earth's weather patterns.
Gonk: There are some seriously ugly character designs here, especially Lex Luthor. This is mostly limited to the elderly males of the cast (which there are a ton of) but even the ostensibly pretty females have weirdly angular faces.
Hypocrite: Catgirl berates one of the 'Batboys' in issue one about killing some soldiers and even beats him up for it. Yet in issue three she clams to have killed the Joker imposter "without an ounce of remorse" and "without a shred of regret" with an arrow through the head. True he couldn't die from that, but she didn't know that at the time.
Monster Clown: For once, there was a reason to highlight this. It's not the Joker, it's Dick Grayson.
Mythology Gag: Hot Gates, the porn star who dresses as Big Barda, is a shout out to the recurring theme of Thermopylae that appears in Frank Miller's work. She was also name dropped in The Dark Knight Returns, so it's also a Call Back.
No One Could Survive That: Saturn Girl has a vision of Catgirl being murdered by the New Joker. Catgirl isn't too worried, as she shot the New Joker with several explosive arrows, and then went to work on him with a hatchet.
No-Holds-Barred Beatdown: Happens to pretty much every character, good or bad. Batman is at his sorriest-looking state ever by the end, going well past "beaten up" and into "disfigured."
Old Superhero: Pretty much the entire cast, with a few exceptions, such as Carrie Kelly, or the new Supergirl (daughter of Superman and Wonder Woman, the fan-ship of many an Elseworlds writer).
Physical God: Wonder Woman calls Superman this. Hal Jordan actually is this.
Strawman Political: The Question is a radical Libertarian, Green Arrow is a radical Marxist. Miller didn't give us any clue which he agrees with, and which, if either, is meant to be correct.
False Dichotomy. Both characters are shown to be ridiculously over the top in their antics. The Question refuses to use anything more technologically advanced than a typewriter (though that could be Properly Paranoid given the setting), and Green Arrow is a hypocritical billionaire Marxist hippie who presumably spent a fortune to get a cybernetic arm when the world is in the throes of a nuclear winter.
Technical Pacifist: Batman at this point is only one out of keeping his word. He clearly does not care about killing enemies anymore, letting subordinates use lethal force liberally, and actually shows a disturbing amount of glee over Hawkboy brutally murdering Luthor. Eventually, he opts to break his code altogether when he happily kills Dick Grayson himself.
Too Soon: Yeah, having half a major city reduced to a smoky ruin not even a year after 9/11? This was unintentional though. The comic was written and drawn before 9/11 but it wasn't published until very little afterwards.
Frank mentioned in documentary on comics that aired on the History Channel that Superman finding that Lois died in Luthor's Kill Sat attack was his way of coping with 9/11.
Villain Decay: Brainiac and Lex Luthor aren't nearly as smart in TDKSA as they are in other stories. In fact, some of the decisions they make are downright moronic.
You Killed My Father: Luthor killed Hawkman and Hawkwoman. Their children, Hawkboy and his sister, want revenge.
Zeerust Canon: published 15 years later, but only takes place two years later.
Zorro Mark: Batman carves one onto Lex Luthor's face.
Catgirl: "The Boss leaves his mark. [we see Batman use a batarang to make the three quick slices] It must mean something to him... "
The film that young Bruce Wayne had just seen with his parents before their demise was "The Mark of Zorro" starring Tyrone Power. Also a Call Back to The Dark Knight Returns when the now retired Wayne breaks down in tears after seeing the movie on TV for the first time in fifty years.
Depending on who you ask, much of Batman's mythology was either inspired by or shamelessly ripped-off from Zorro. Don Diego Rivera was rich and acted like an effete douchebag most of the time, but operated as a vigilante out of a cave beneath his mansion with the aid of his butler. Not exactly unfamiliar.