Special notes: cities and unnamed civilians
In some, if not all, of these nasty cases that have taken place since the early 1990s with established characters being killed off and villified, some of those who've suffered the worst next to them include whole cities and even tons of nameless civilians. DC is a serious offender in this, and Marvel has a few cases of their own too. This will be a special list of all cases I can think of where innocent nameless bystanders were also turned into horrific sacrifices.
Here is one of the first crossovers where quite a few people ended up in a pool of blood. The idea of this reprehensible story was to introduce at least a few new superhero characters (including Anima, Argus, Gunfire and Hitman), most of whom vanished after barely 2 years. A race of aliens who can do things like what Aliens, The Terminator and Predator already featured, comes to earth to suck the spinal fluid out of humans at random, or even devour them altogether, and shed quite a bit of blood in the process. Challenging question: did they truly need to make this a bloodsoaked story in order to introduce these newcomers to the superhero community? Or couldn't they have done so in their own stand-alone stories, even within a miniseries of their own?
When the editors who mandated this can only resort to crossovers as a means of introducing new characters, or even serving as a lead-in to the same, that's what shows a severe lack of creativity, and an inability to create stories that can stand and be marketed on their own. It all culminated in a finale titled Bloodbath, which caps it with a manhole cover.
This was certainly one of the most notable, when Mongul destroyed Hal Jordan's hometown, and later on, Hal went insane in despair. So many people may have gone down courtesy of this, and what was the point? Apparently, to destroy almost everything that made the GL Corp's amazing background, which signals that, despite initial work on nostalgic storytelling in the 90s, they were certainly not going in that direction with GL, if they were going to otherwise make Kyle Rayner the only Green Lantern for at least a few years.
When Geoff Johns took over the Flash, there was alarming violence and destruction on a level probably never seen before in the Scarlet Speedster's title, and the aforementioned Blood Will Run atrocity certainly saw quite a few bodies piled up in the morgue. And, even if the rest of his initial run didn't have as many bodies, it still featured more than enough wanton destruction and violence to sink a ship. (Did I mention issue 195, where the Top used a ludicrous eyesight bending power to cause Wally West quite a vomit-inducing headache? And if Wally could get his head knocked up that bad, we can only wonder if everyone else on the dock...)
This was the name of a fictionalized European country featured in the Ultron Unlimited storyline in the Avengers in 1998 that got wiped out by Ultron and an army of other robots he built. I have more respect for Kurt Busiek than I do for Geoff Johns, but this, to be honest, has me feeling depressed and wondering today if it was a good idea to take Ultron that far as a supervillain. After all, it would be one thing if Ultron had slaughtered a small number of people, but a whole country? Unless we look at this as a section of the former USSR, this can be troubling, and even bothersome as to whether it works or not.
Happened just recently, and was definitely one of the most disgusting and poorly written storylines, with not just Lian Harper biting the bullet, but also close to 100,000 other unnamed souls in Green Arrow's main home burg. James Robinson and company at DC fell back on the same mistake made with Green Lantern in 1994, coughing out a pointless story nobody asked for, and Robinson threw away his credibility as a writer.
This is what the list will comprise for now. In time, I'll see if there's any more input I can add. For now, I will say that DC is definitely the worse offender in terms of over-the-top violence on a global scale, and has been since as early as 1993. Also the most pointless when it comes to their awful violence-laden stunts.