These fans have been indulged since. 

Oops!  I forgot Michael Fleisher & Jim Aparo's THE SPECTRE series in ADVENTURE COMICS (1974-75)!  Now THAT was dark!

I understand the origin for that was that editor Joe Orlando got mugged and worked with Fleisher on the plots to really punish criminals in gruesome ways.  The horrible deaths might have been lifted from EC comics short stories years earlier, but here they were committed by a fairly mainstream super-hero.  So, here, the real-life trauma of a mugging led to the beginning of darkening for DC's otherwise kid-friendly line.

(Of course, Harlan Ellison--who can be dark himself--called Fleisher's novel CHASING HAIRY "the product of a sick mind" in a COMICS JOURNAL interview and also said the SPECTRE run was cancelled when DC "realized they had turned loose a lunatic on the world"...and got sued by Fleisher!)

Greg, Gorilla Grodd, Sam Simeon's uncle, snapped Angel O'Day's sister Dumb Bunny's neck by twisting her head completely around at the end of an issue in Phil Foglio's "Angel and the Ape" mini-series because... Continuity! And... Humor! 

I could just have easily cited Bizarro, you remember, funny Bizarro? punching Roy Lincoln's Human Bomb "until the pretty lights went out" or the use of Chemo as a chemical bomb to wipe out the city of Bludhaven in Infinite Crisis. Or any number of instances...

I did not mention Michael Fleischer's Spectre series because it really did not set any other dominoes in motion. The horror with which the readers and industry reacted to what were actually fairly tame EC-style demises showed that the super-hero industry really was not ready for such excesses at the time. It should also be noted that Fleischer had no use for continuity with the rest of the DC line, going so far as to have someone compare a bespectacled character to Clark Kent, who everyone knows is secretly Superman... In the Spectre's world, Superman was just a comic book character. The Fleischer/Aparo Spectre was a falling domino that really didn't hit any others, in part by design.

I'm with Greg on the idea of the initial stories being fine, and the subsequent, lesser works being more responsible for where we are today. Most of the examples I mentioned, the GL/GA stories, Miller's Daredevil, Moore's Swamp Thing, Dark Knight, are excellent (the Foglio story excepted especially) and I wouldn't want to see the industry without them. Unfortunately, like Gardner Fox's introduction of Earth-2, it wasn't that first domino that caused problems so much as it was all of the far, far less talented dominoes running into line afterwards, screaming, "Me too! Me too!" that brought about wreck and ruin. 

Fox brought about Earth-2 so the Golden Age Heroes could still have a place in the stories and yet be out of everyone's way at the same time. No company-wide "legacy" heroes on Fox's watch, although he did give us the altogether charming Zatanna, first of the legacy characters and the first major company-wide cross-title crossover as well. Again, something that worked fine at the time, but sagged noticeably under the weight of wannabes piling on top of it... 

Fox also gave us Earth-3, the villainous Earth, which was fine; Earth-A, a Johnny Thunder-created reality which erased itself at the end of the story, and sadly, his only real mis-step, Earth-Prime, "our" Earth. Once those were in play, everyone wanted to play the Parallel Earth game as well, to explain where the National Comics heroes had been all this time, and the Fawcett heroes, and one for why Bob Haney stories didn't seem to fit anywhere, and one for funny animals, and another one for the other set of funny animals those same creators made up... It got old fast, and it did not have to. 

Had the writers of those other stories done what Fox did, apply imagination to creatively solve a problem, they could easily have avoided the Crisis mentality that still dominates and overwhelms editorial policy at DC. True, without Fox and Schwartz there to kick things off, the others would never have been bright enough to come up with the Multiverse on their own, just as Dark Knight gave lease to avenues of storytelling the wannabes could never have dreamed up by themselves. "No one wants to be first, but everyone wants to be second" is a business world truism, in part because being first is really pretty hard. Being second? Pffft! Piece of cake!

GL/GA. Gwen Stacy. Jean Grey. Dark Knight. We'd be poorer without those first dominoes. It's the ones after them unfortunately that really collapse the whole thing. Sadly, this is an industry rather than an artists' retreat and in business, nothing exceeds like excess.

Eric, thank you for the kind words. Every now and again, I think about starting a blog to editorialize and extemporize at will. Then I lie down until the feeling goes away. :-)

Your point about the mugging is an interesting one! I've read that Frank Miller being mugged just outside his apartment led to a lot of the darkness and vengeance-seeking in his Daredevil. 

Everyone's bright, shiny, and new, over and over again, so... yay, right?

There is some small comfort in knowing that the maniacs and sad sacks of today really aren't considered to be the same versions you and I grew up with... In fact, with the difference in our ages, the ones you had are very likely not the ones I did... :-)

We shouldn't let the petty little people standing on the shoulders of giants make us forget about the giants, y'know?

Something that came to mind during the recent Gay Sulu controversy over in the land of STAR TREK--there used to be (and should be) a certain unspoken deal between creators and their audience. Characters have characteristics. These are the traits which define them, be they physical traits, personalities, or interpersonal relationships. Since they're fictional constructs, we readers need a fairly high degree of consistency in order to latch onto them. 

Once you start pulling at threads, the whole rug can pretty quickly end up being pulled out from under the audience. Without consistency, the whole thing falls apart, and there's no way to really get attached to these fictional constructs and become emotionally invested in them. "This is all pretend, so we can reshape and reboot things to suit our whims" is not exactly the best foundation for generating a sense of verismilitude and wonder in your audience.

When I read a comic, I don't want to think, "Oh, Writer X is going out of his way to 'fix' something, and, in so doing, is writing this character wrong". I want the suspension of disbelief that comes from good writing. Now, when I pick up, say, a Lee-Kirby issue of FANTASTIC FOUR, my mind may be at least partly in Historical Analysis mode, but I always--ALWAYS--get sucked into the stories and the characters. They feel like real people, like old friends. I believe in them. That's the magic of good writing. 

ITEM: Jim Shooter started writing Legion of Super-Heroes, and introduced two big elements. First, Karate Kid - a legionnaire whose power solely relied on hitting people. Not shocking them, not mentally putting them to sleep, not hemming them in a ring of fire - his power only worked when he beat people up. Other physical heroes up to that point in the Silver Age didn't seem to rely on fisticuffs... even Batman and Robin had other gimmicks besides beating the tar out of villains.

Also, Shooter assembled a team of super villains, and in the same story, killed one of his new characters. For good, for permanent, until the next reboot. Ferro Lad wasn't coming back. Yeah, Uncle Ben and Bucky were dead... but it wasn't quite the same.

ITEM: The death of Gwen Stacy, as already noted. This crossed a line at Marvel that I think couldn't be crossed back. Yes, as shown, Uncle Ben and Bucky were dead, but one was the impetus of creating a hero, and the other didn't really in the Silver Age (even if it was related during it.)

ITEM: The Punisher. The upshot of this character is that he was the ultimate avenger, killing criminals for their crimes to avenge his family. KILLING criminals. This just wasn't done until Castle showed up. That seems to be the start of the big shadow of "realistic" characters.

It might also have been inevitable that darkness was going to come into the books when they started dealing more with human drama rather than super heroics. I guess that started happening at Marvel, but once we got into the motivations of Karen Page or Jane Foster or Gwen Stacy, we had to start connecting with them... and to heighten the suspense when they were in peril, it had to be a connection sort of peril, so that we felt more about what was happening.