In the real world, death is the end, but for the heroes of DC, permanent death is more of a theoretical concept. It makes sense when you think about it; characters who have been around for decades can't disappear for good or publishers would have a serious deficit where superheroes are concerned. For DC, that means you can bump off Batman or Superman, but they're going to have to come back sooner or later or risk a full-on fan uprising.
And that's pretty much how things go in the DC Universe. A character everyone loves sacrifices themselves for the greater good, their friends and readers get emotional, and life goes on. After a little while, they come back - maybe a little stronger, sometimes a little wiser, but they almost always come back.
Almost all of DC's biggest heroes have met their maker at some point, but those ends weren't exactly permanent. In a lot of cases, fans focused more on counting the days until they came back than mourning the losses.
How'd He Go?: DC let the world know it was going to eliminate the Man of Steel, and that's exactly what they did in 1993. Doomsday had come to Earth, and nobody could stop him as he tore his way across North America looking for a Kryptonian to fight. Superman met his challenger, and the two engaged in the toughest fight of Superman's life. They beat each other so badly that both the hero and destroyer expired with their last punch.
How Long Was He Gone?: The "Death of Superman" event was immediately followed by "Funeral for a Friend," "Reign of the Supermen," and "Return of Superman." Superman came back after about one year in the DC Universe and about seven months in the real world.
How'd He Come Back?: After Superman perished, his body was taken from his crypt by the Eradicator, an ancient Kryptonian device that was masquerading as one of the new Supermen in the DC Universe. It placed Kal-El inside the regeneration matrix, which eventually revived the hero. When he returned, Superman sported a black costume with silver bracers and a silver "S" symbol... and for some reason, he had a mullet.457An obviously temporary end?
How'd He Go?: Bruce Wayne/Batman met his end in Final Crisis, which featured Darkseid attempting to mind-control the Dark Knight. Batman escaped Darkseid's control and successfully shot the Apkolopitan overlord with a super-bullet capable of slaying a New God. At the same time, Darkseid fired off his Omega Beams, killing the Caped Crusader. He was later seen being held in Superman's arms, a lifeless and charred corpse.
How Long Was He Gone?: Bruce was gone for a good 23 months in the real world, and that's a long time for DC to bench one of its most popular characters. Of course, others filled his shoes while he was out of the picture, notably Dick Grayson's celebrated Black Mirror story arc, but the DC Universe just isn't the same without Bruce Wayne.
How'd He Come Back?: So, here's the thing: Batman never actually passed away. It was all an intricate plot of Darkseid's and Batman's return was detailed in Batman: The Return of Bruce Wayne. Batman's consciousness was lost in time, having been displaced in the timestream by Darkseid. He had amnesia and had to overcome his missing memories to make it back to the right time and place: present-day Gotham City. He had to fight his way through six time periods before he could make it to the present-day, but he did. When that happened, the Omega Energy still threatened to destroy the universe, which was Darkseid's plan all along, so the Justice League stopped his heart (actually killing him) to let the energy dissipate. He had some visions, woke up, and put his costume back on to once more become the Dark Knight.347An obviously temporary end?
How'd He Go?: In Batman Incorporated #8, Talia al Ghul sent The Heretic/The Fatherless, a fully-grown clone of Damian, to eliminate her and Batman's son. The young Robin fought against his berserker clone — he put up a pretty good fight – but in the end, he was impaled on a sword.
How Long Was He Gone?: Damian remained dead for about a full year, and it was a tough one for Batman/his father. The kid was truly gone, and while it seemed like there was no possible way to bring him back, Bruce wasn't willing to accept that as an answer.
How'd He Come Back?: Bruce didn't take his son's passing lying down, and he did absolutely everything possible to resurrect him. He met up with Frankenstein's Monster, he tried the Lazarus Pit as a possible option, and finally, he literally went to hell and back in Batman and Robin #38 to bring him back. He got his body from Darkseid, and successfully resurrected the boy a year after he passed.171An obviously temporary end?
How'd He Go?: Green Arrow/Oliver Queen was never the type of guy to avoid a fight. When he learned of Hyrax's plot to bomb American cities, he found a way to make it onto a plane carrying one to Metropolis. Ollie was the only one remaining after a firefight on the plane and he was stuck with a bullet in his gut and the failsafe in his hand. Superman arrived and offered to cut off his friend's arm to save his skin, but Ollie wouldn't hear it. Arrow piloted the plane safely away from Metropolis and, with Superman at his side, Ollie removed his hand, detonating the device and sacrificing himself to save the day.
How'd He Come Back?: Throughout most of his superhero career, Ollie worked side by side with Hal Jordan, the Green Lantern. Jordan went a bit off the rails at one point, and he merged with the fear entity known as Parallax. He was able to overcome the entity using willpower, giving him the power to reignite the Sun, and just before he succumbed to the rigors of being a cosmic god on borrowed time, he resurrected his buddy as one final act of good.174An obviously temporary end?