For decades, superhero death was an extreme rarity. Over time, it began to happen more and more; however, as death became more prevalent, so too did superhero resurrections. There's a reason why both Joe Quesada and Dan Didio have, at various points in time, come up with "dead is dead" rules, as the revolving door of comic book death seemed to just get ridiculous at times.

RELATED: The 15 Most Heroic Superhero Deaths of All-Time

However, for some characters, when they knock on heaven's door, the door closes shut behind them and they actually don't get to return to life. We decided that we would feature the 15 characters that we are most shocked no one has resurrected yet. The characters have to have remain dead for at least five years for us to count them as "staying dead." New versions of DC characters in the new 52 are confusing, so we'll just count whether they stayed dead for five years and didn't come back to life by the start of the new 52.

15 Nomad

Jack Monroe's Nomad prepares for battle

Jack Monroe was introduced during Steve Englehart's run on "Captain America," when he came up with the idea of actually addressing the fact that Marvel put out a "Commie smashing" version of Captain America in the 1950s (after "Captain America Comics" had been out of print for a few years). Englehart was famous for using odd little bits of Marvel's comic book past as fodder for stories (like when he re-introduced Marvel's popular Archie-knockoff, Patsy Walker, into the "Beast" feature in "Amazing Adventures"). Englehart revealed that the 1950s Captain America and Bucky were actually people who volunteered to fill in for Cap and Bucky and were then put into suspended animation, themselves.

William Burnside, the Captain America, became a villain, but his Bucky, Jack Monroe, eventually became the hero known as Nomad. Nomad had his own title in the 1990s, a compelling journey across the back roads of America by writer Fabian Nicieza. Nomad fell by the wayside over the years and in his "Winter Soldier" storyline, Ed Brubaker had Winter Soldier (the real Bucky) kill Monroe. In the years since, though, so many "Captain America" supporting cast members, like D-Man and even Burnside, have been used so well that it's sort of a shame that we haven't been able to see what Nick Spencer could do with Jack Monroe.

14 Dolphin

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You might wonder why, exactly, we should worry about the death of a character who was so forgotten that she was literally part of a team that called themselves "The Forgotten Heroes." However, do note that Animal Man was also a member of the Forgotten Heroes, as was Rick Flag, so being forgotten at one point doesn't make you a bad character.

In addition, as soon as Peter David made her a recurring character in the pages of "Aquaman," Dolphin has really resonated as a presence, even if her relationship (and marriage) to Aqualad/Tempest was not the best developed comic book romance (and the birth of their child must have been one of the most ignored superhero family births of the decade). However, her death during "Infinite Crisis" was so blase that her legacy is a bit of a shame. Another is that nobody has made an attempt to revamp her as a character in the New 52. The closest she really got was a cameo in "Blackest Night."

13 Shard

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Shard (which, okay, we admit is not a great superhero name) was the younger sister of Bishop of the X-Men. Like her big brother, she was a member of the XSE (Xavier's Security Enforcers) in the future. She was infected by a strange disease and died in the future, but not before her brother pulled off a desperate gamble and had her, in effect, digitized and sent into a holographic matrix. Her mutant power was manipulating photonic energy and firing it as blasts. Now that she was photonic energy, she could continue to control herself that way.

She ended up in the past with her brother and actually split from him, becoming a member of the government-sponsored mutant team, X-Factor. When that team broke up, however, she ultimately went back to the future, where her brother was forced (by her) to fully absorb all of her energy to defeat their fellow adversary, Trevor Fitzroy (who Shard had dated in the past). But come on, we're talking a being made out of energy here! Is there anyone easier to put back together than a being made out of energy?

12 Pantha

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When the "New Titans" were revamped in the early 1990s, one of the new additions to the team was the Wolverine-esque hero known as Pantha. She had a mysterious past and was prone to berserker rages, but by the end of her tenure with the Titans, she had managed to settle down a bit with her teammate, Red Star, and the genetically mutated being known as Baby Wildebeest, who viewed her as his mother. They all formed a cute little family unit.

However, during "Infinite Crisis," when all the Titans ever got together to stand up to Superboy Prime to defend their friend, Superboy, Pantha (and Baby Wildebeest) were among those heroes who were slaughtered by Prime. Since she didn't have a healing power (one of the areas where she should have been more like Wolverine), it made sense for Pantha not to return, but it's still a shame.

11 Thunderbird

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This is one of those instances where we are not saying that this character should return, just that we are surprised that he has not come back. When the All-New, All-Different X-Men debuted in "Giant Size X-Men" #1 in 1975, no one knew that they would become such iconic characters. So, when Len Wein and Dave Cockrum decided to kill off one of the team members in the team's first mission after becoming the official new X-Men, they did not know that they were debating between a number of future icons. Ultimately, they ended up choosing to kill the Native American hero, Thunderbird (John Proudstar).

Therefore, since the other heroes have all become such iconic characters, who's to say that Thunderbird might not have that same potential? His younger brother, James Proadstar, has become a notable character (going by the name Warpath), but there seems like there still might be potential for a hero with his powers and background.

10 Thunderstrike

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Eric Masterson, Thunderstrike, is a fascinating character because his creators, Tom DeFalco and Ron Frenz, actually got to direct him throughout his entire comic career, which lasted nearly a decade. They introduced him in the pages of "Thor" and then had him temporarily take over as Thor for over a year (while the real Thor was incommunicado). Once the real Thor returned, DeFalco and Frenz left the main book and launched a new ongoing title starring Masterson, who was now given an enchanted mace and became known as Thunderstrike.

When "Thunderstrike" came to a close, Eric Masterson sacrificed himself to stop the evil death god, Seth. DeFalco and Frenz said that they always intended for Masterson to die whenever his series ended, and while we believe that, we still wish he could return. He's magic, so he should be easy enough to bring back from the dead. Thor's returned from the dead, what, 40 times by now?

9 Genis-Vell

Marvel Captain Marvel Genis-Vell

One of the few new characters introduced in Marvel's 1993 Annuals that stuck around was Genis-Vell, the son of the original Marvel Captain Marvel, the Kree warrior Mar-Vell. After going by the name Legacy at first (as he was a legacy hero, naturally), he eventually adopted the Captain Marvel name in the mid-1990s. However, it wasn't until the very end of the decade that he really got a big break, when he was included in Kurt Busiek and Carlos Pacheco's "Avengers Forever" maxi-series as a future member of the Avengers.

That series led to an ongoing by Peter David where Captain Marvel shared bodies with Rick Jones, just like how Jones had shared a body with Genis-Vell's father in the past. After two excellent ongoing series by David ended, Genis-Vell ended up joining the Thunderbolts under the codename Photon (a joke, because the name was the one that Monica Rambeau had taken after Genis had taken the "Captain Marvel" name, which she had been using at the time). However, he died during a "Thunderbolts" story and has somehow not returned since.

8 Manhunter

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Often in comics, you'll have situations where certain creators ask other creators to lay off particular characters. As an example, for years, Stan Lee was the only writer "allowed" to write Silver Surfer solo stories. However, most of the time (including the case of Lee and Silver Surfer), those deals don't exactly hold up. For instance: there was that time Marvel promised Frank Miller that they would not bring Elekra back without his permission... and then just decided to do it anyway.

So, the fact that DC has continued to pay respect to the conclusion of Archie Goodwin and Walter Simonson's classic "Manhunter" series from the pages of "Detective Comics" is amazing. The series starred Paul Kirk, the seemingly dead Golden Age Manhunter, who learned that he was a clone, as part of an attempt to form an army of clones of Kirk. He then sacrificed himself to kill them all and that's been it for the character, despite multiple continuity reboots since.

7 Phyla-Vell

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Initially introduced as a bit of a joke in the pages of "Captain Marvel," Phyla-Vell (her name is a pun based on Genis-Vell's name) was created out of nowhere when her brother rebooted the universe, leaving everything pretty much the same, but slightly different -- including Genis now having a sister that he didn't have before. She temporarily took over the Captain Marvel title from her brother, but by the end of the series, was involved with the cosmic hero, Moondragon.

Phyla and Moondragon were a couple throughout the two "Annihilation" crossovers, where Phyla found Wendell Vaughn's quantum bands and became the new Quasar. After Moondragon died, Phylla worked out a deal to bring her back, by being killed herself and becoming Martyr, the servant of Oblivion. However, she eventually was manipulated into freeing a resurrected Thanos. In the process, she was murdered. She is still dead... which is weird, because she had a great relationship going with Moondragon (which is more than her brother could say) and, as a cosmic character who already came back from the dead once, she should be very easy to bring back.

6 Pretty Much All of X-Statix

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One of the main concepts of Peter Milligan and Mike Allred's "X-Force" run was that characters would die. In fact, the first issue saw almost all of the members of the team get killed off. After that, though, the established members of the team (especially the Anarchist, U-Go-Girl and Mister Sensitive) became developed and were not killed off... until the end of the "X-Force" series. There was a whole storyline that revolved around the very idea of comic book death. In the end, U-Go-Girl bit the dust.

The team then rebooted as X-Statix and the book became more and more satirical as time went by. In the final issue of the series, everyone on the team (except for Doop) was killed. One of the members, Dead Girl, had her own mini-series in the time since, but she did so as a ghost. The characters of X-Statix are so good that while we get allowing Milligan to get the ending that he wanted, we also get the idea of bringing the characters back down the line if a writer wants to write them.

5 Dorothy Spinner

Doom Patrol member Dorothy Spinner creates a monster

The strangest thing about Dorothy Spinner is that while she became one of the key members of Grant Morrison's acclaimed "Doom Patrol" run, she was actually introduced in the previous run by Paul Kupperburg, as a strange riff on Dorothy from "The Wizard of Oz." She was just a one-off character, but when Morrison took the book over, he had her join the team, and the friendship between Cliff "Robotman" Steel and Dorothy became a major part of the series (he helped her deal with her problems of growing up, like how she got her first period in an early story).

Dorothy's power was to create imaginary friends and have them come to life. Even after Morrison left, she remained a member of the Doom Patrol, but she was not part of later attempts to relaunch the title. She was revealed to be in a coma during John Arcudi's attempt at relaunching "Doom Patrol," and she died at the end of that series. Dorothy was a fascinating character during Morrison's run, so it is a shame that no other writer has found an interest in doing anything with her. It remains to be seen whether she will make an appearance in Gerard Way and Nick Derington's "Doom Patrol" at DC's newest imprint, Young Animal.

4 Arsenic

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Pretty much all of the original Runaways members were very well-developed, characterization-wise, by Brian K. Vaughan and Adrian Alphona, so the series really could not stand to lose any of them. It was still a particular shame to lose Gertrude "Arsenic" Yorkes, who brought a unique viewpoint to the series. Gertrude was one of the first members of the Runaways to really embrace the idea of becoming superheroes (she was bonded with a future dinosaur, who she dubbed "Old Lace," so that they'd be Arsenic and Old Lace).

She began dating her teammate, Chase, but her self-doubt caused her to question their relationship, as did the fact that Chase kissed one of their other teammates, Nico. The team was visited by Gertrude of the future, who came to warn them about a new teammate, Victor Mancha. After that was resolved, Gertrude was sadly killed in a battle. She transferred control of Old Lace to Chase before she died. The weird thing is, though -- and why she is particularly so high on the list -- is that at the end of the last "Runaways" volume, they seemed to be setting up a possible return for Gertrude, but never went anywhere with it.

3 Azrael

azrael

Jean-Paul Valley was out of his element as Batman, and really, that was the main reason why Valley was chosen to be the new Dark Knight, as the writers and editors of "Batman" wanted to show why Bruce Wayne was still the one-and-only. However, after he left the role in a disgrace, he returned to his roots as Azrael, who was a cool character in his own right.

Jean-Paul Valley was part of a twisted religious order known as the Order of St. Dumas. He learned that he was the latest in a long line of assassins, and was brainwashed into becoming Azrael. While Batman was helping him break from his programming, he had to take over the role (due to Bruce's injuries during "Knightfall"). Azrael's ongoing title lasted 100 issues, which is super impressive. He seemed to die at the end of the final issue, but it was really handled off-panel, so he could easily return. For whatever reason, though, he is considered dead as a doorknob at DC. There was even already a new Azrael, Michael Lane. However, in the New 52, there was a new Jean-Paul Valley introduced in "Batman and Robin Eternal."

2 Mar-Vell

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When Jim Starlin killed off Captain Marvel (Mar-Vell of the Kree) in the first Marvel Graphic Novel, it was a big deal; not just because he was one of the most famous superheroes ever to be killed at the time (characters who carried their own titles typically were not killed off), but in HOW he did it, with Mar-Vell dying from cancer rather than falling in battle. It's a wonderfully written story, showing a hero struggling with mortality, but the question is whether Starlin's great graphic novel is enough to take such a great character like Mar-Vell off the table for future stories.

Marvel Comics teased returning Captain Marvel to life during "Civil War," but he turned out instead to be a Skrull. With Carol Danvers now as Captain Marvel, there's no clear role for Mar-Vell in the Marvel Universe, but he might make for an interesting supporting cast member of Carol's own series, allowing Mar-Vell to take the role that Carol served in early Mar-Vell stories.

1 Jean Grey

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At the time of Grant Morrison's departure from Marvel in the early 2000s, it seemed like the publisher was raring to get rid of as much of his "New X-Men" run as they could, with Magneto impersonating Xorn and then famously dying in "New X-Men" #150... but then being revealed as alive (and never having taken on the identity of Xorn) in "Excalibur" #1, which came out right after "New X-Men" #150. It was a weird time.

Yet somehow, the only thing that has permanently stayed around (Cyclops and Emma Frost broke up and Beast evolved past his cat-form) from Morrison's run is Jean Grey's death at the hands of Magneto (or whoever it was retconned to be in that fight) in "New X-Men" #150 (right before Wolverine separated Xorn's head from his body). In one of his final issues on the series, Morrison showed Jean Grey surviving Wolverine gutting her and surviving being sent into the sun. And yet, Magneto/Xorn quickly kills her. She was brought back briefly in "Phoenix: Warsong," but she hasn't returned since. But c'mon, her name was the Phoenix! She's all about returning from the dead!

Which dead superhero would you most like to see make a return?