Depending on how you feel, this is either long-promised or long-dreaded or, more objectively, not long anything because I only promised it here just two days ago.
Superhero comics weren't doing completely awful in 1986, actually--you could still find them on newsstands, a comic selling 100,000 copies was in trouble and John Byrne was still relevant. More than that, there were 3 major miniseries of note that at the time had a tremendous amount of buzz behind them and would go on to be the cornerstones of the superhero canon.
In one case, it's richly deserved--Watchmen is unassailably quality work which uses the grammar of superhero comics to its maximum potential. Combined with a grittier, more realistic take on the mindset of the costumed hero (which postulates that dressing up and fighting crime requires equal parts perversion and mental illness) and views the idea of saving the world in a more sinister light than we'd seen in superhero comics thus far.
In a fairer world we'd remember the way it expanded the vistas of the art form ("Look! We can do this! We can do so much more than we thought!") It should have been the final kiss-off to the slavish devotion to replicating the stories of the 60's and 70's with not much change and bringing a little more intellectualism to superhero comics. If the medium has ceased finding newer, younger audiences to replace the old, this was certainly one way to go forward.
Unfortunately, the main lesson people seem to have taken from it almost 25 years after is "Man, Rorshach is KEWL." Ever since then, superhero comics have been host to a number of imitators, all of whom take the surface elements with no knowledge of how they worked so well or why and the net result is like having the chassis of a Lamborghini Gallardo but the engine of a Go-cart.
(As an aside, I should mention my favourite moments featuring Rorshach in Watchmen aren't the ones where he's breaking bad on people, but the very few moments of humanity he exhibits--apologising to Nite Owl, for one, and the last confrontation with the landlady as well. It doesn't humanise him, but rather those moments of humanity throw his basic inhumanity into sharp relief.)
This was, of course, only the beginning. Running along with this was The Dark Knight Returns, written by Frank Miller, who you might remember I not-so-subtly implied was mentally ill yesterday. Dark Knight doesn't exactly argue against that--read today, with the benefit of hindsight it's garish, loud and borderline obnoxious, and blazed its trail more because Batman didn't usually shove glass in people's arms or shoot them with machine guns and generally be Death Wish or Dirty Harry tarted up as a Batman comic.
(I realise this is not a popularly-held notion, but really . . .I just re-read this thing and it's aged dreadfully. We should have known, even then.)
The harbingers of Miller's obsessions are all there--strength is prized above all else, and how much ass you kick is the barometer of everything that matters. To object to this rather simplistic worldview that force is the ultimate authority is to willingly grab ankle and pucker up to a world of spineless sheep or weasely manipulators. By returning to the world and illustrating the value of the five-fingered justice system, Batman is venerated like a messiah.
Seriously. From the full-page shots of Batman looming over awed bystanders, Carrie Kelly's unquestioning devotion to Batman, the former mutants idolizing him a mere five seconds after the fight with the mutant leader, but MOST of all, Lana Lang's utterly ridiculous (and, from all evidence, completely sincerely meant) "There is a MAN out there and he has shown us we can RESIST" speech. I dare you to read it and not roll your eyes.
Intellectually, of course, all this is rubbish, assuming you're above the age of 14 and don't spend your time concocting revenge against people who bullied you in high school.
It's been suggested that Dark Knight is best read as parody, and had these themes solely been contained within this book, I might believe that. Bust seeing as how Miller has returned to this basic concept of ass-kickery uber alles over and over and over again (and is still doing it in All-Star Batman and Robin: Adventures Behind The Sim Meridian) I am left to assume that no, he Really Means It. Miller is not only obsessed with "giving Batman his balls back" (whatever that means) his thesis in his later works seems to be that the real problem is that everyone needs their balls back and if we just returned to the halcyon days of say, Sparta, everything else would work out. Also, Batman totally needs to punch out Osama Bin Laden so that the healing can finally begin.
Naturally, everyone in comics took the wrong lesson from this, and a story that, while impactfully told, really should have been weighed about as much as that book where Batman is a vampire or hunting Jack the Ripper or whatever, has become another part of the dreary template of superhero comics today. Sure it was a shot across the bow in terms of "comics aren't for kids!" but replacing it with "Comics are for socially maladjusted arrested adolescents" was hardly and improvement.
Oddly prescient as it turned out, but not an improvement by any means.
The third book, much less regarded than the other two but a trend-setter in its own right was Squadron Supreme. While it's not mentioned in the same breath as Watchmen or Dark Knight, we certainly wouldn't have had Kingdom Come without it. Unlike our two previous examples, SS doesn't push things forward in terms of content as much as it does in terms of subject matter. Squadron Supreme simply tries to be The Last Justice League Story and it succeeds pretty well in that.
For those of you who don't know it (or only know the 2000-era version) it goes something like this: The Squadron, basically a one-to-one analog for DC's Justice League has to save the world in the wake of an alien takeover. To do so, they establish order, seek to eliminate the threat of disease, and eradicate the threat of crime. In a word, Utopia.
Utopia, unfortunately, is paved with slippery slopes. Eliminating crime involves screwing with the minds of criminals, often against their will. This then becomes a can of worms that splits the Squadron apart when the "mind-changing" device is used by a member of the Squadron on another member.
And that's just the start of things. Squadron Supreme asks a lot of very intriguing questions about superheroes and just how attainable the idea of saving the world is. Is utopia worth anything if a group of elites hands it to the man on the street? Is utopia justified as an end if the means are, at best, morally questionable? If a utopia is only as good as those who create it, what happens when the creators are gone--can you really trust that the next generation will be as good as you have been? What are the limits of what a superhero can do. To further read about the themes explored in this series, there's a great article here that is well worth your time, as is the article here, that takes you through the series in a less academic manner.
It's not all it should be, as a book--while this is undoubtedly Mark Gruenwald's vision, it lacks the coherence of the two previous books (It's hobbled by the lack of no consistent art team and a number of fairly generic fill-in artists) it has, subtly, informed on the superhero comics that followed it--I mentioned Kingdom Come earlier, but The Authority also has elements of the themes explored here (though obviously not quite in the same ways) the 2000-era revisiting seems to be an in-name-only version, and departs both from the initial concept (It's an off-brand Justice League) and the themes addressed in the mini.
Unlike the first two, Squadron Supreme isn't quite as responsible for terrible antecedents, mostly because it's not as well known as our previous examples, except among people who were doing superhero comics or coming up through the ranks at the time. In hindsight it exists mainly as a curious bridge between the old-school Roy Thomas-esque superheroing of yore, but with a bit more thought behind it.
To sum up, the tragedy here is not that these books got undeserved fame 23 years ago--most of them, by virtue of quality or sheer audacity, deserved the excitement they generated at the time. The tragedy is that not only were the wrong lessons learned by those who came after, but even more, they failed to push the potential boundaries further after being shown how to do exactly that. And in the meantime, a whole generation of readers (potential and otherwise) came and went, finding nothing pitched to their interest or experience (more or less--like it or hate it, the Image stuff, at the time, did inject a lot of energy into superhero comics that came from another place than this) and look at the damn mess.
Almost as quarter century later, we're going in circles and wondering why we haven't made it very far.