Agents of Atlas: According to Namor, the Sub-Mariner #50-51, Namora had been dead for decades. It turns out her corpse was just a hologram hiding her comatose body. Then she wakes up and joins the team.
Guardian died and survived by being transported to Ganymede, but this was a story made up by Delphine Courtney, which turned out to be true anyway.
Northstar dies in Wolverine: Enemy of the State, gets resurrected, gets brainwashed twice, and gets better.
Marrina Smallwood is killed by Namor in Avengers #293, returns in Dark Reign, is again killed by Namor, and returns in Chaos War, along with the rest of the team killed by The Collective in New Avengers, except Puck, who returns in Alpha Flight vol 4 #2, claiming to have fought his way out of Hell.
Wonder Man dies in Avengers #9. His body is buried in a grave, stolen by Grim Reaper, temporarily revived as part of the Legion of the Unliving, and revived as a zombie by Black Talon, but it turns out he was in a death-like catatonic state the entire time. Wonder Man dies again in Force Works, and is revived in Avengers vol 3 #3.
Wonder Man's brother, the ironically-named supervillain Grim Reaper, has himself died no less than six times. Four of those deaths happened in the same six year stretch, to boot.
Like the Justice League over at the Distinguised Competition the The Avengers have actually enacted plans that involved the entire team dying with the assumption that they'd come back to life. The Avengers did it to rescue teammates from the Grandmaster who'd arranged their deaths so he could use them as pawns in the afterlife (being dead himself at the time) by drinking poison and more-or-less assuming they'd figure out a way to get back to life once they'd sorted everything out on the other side.
In Avengers Undercover, Arcade dies in issue #3, until issue #7 reveals it was actually a clone that had died.
Secret Avengers had an issue where Black Widow interrogated a group of gossip columnists after they published a story claiming that Bucky Barnes survived his apparent death in Fear Itself. She soon discovered that the columnists fabricated the story because they figured Barnes would be resurrected soon enough anyway, given how frequent such returns are in the Marvel Universe.
This was a triple-somersault Lampshade Hanging, since the real reason Widow was interrogating them, was because she knew that Barnes had faked his death, and was worried the story had leaked. The two "big deaths" of Fear Itself (Barnes and Thor) were both immediately shown to be temporary, since the creators knew no one would believe they were permanent.
Captain America: Winter Soldier: Bucky didn't die, but fell into the freezing ocean, was found by a Russian submarine, kept in cryostasis, and was brainwashed to become the Winter Soldier. The Red Skull is assassinated, but being in contact with the cosmic cube allowed his consciousness to be transferred.
He'd previously died of old age, but Arnim Zola place his mind in a clone of Captain America's body.
Hitler died from the android Human Torch, but several clones were made. Arnim Zola transferred Hitler's mind to the clone that became Hate-Monger.
Sharon Carter died in Captain America #237, but really her death was staged by SHIELD. She died from an explosion in Captain America vol 7 #10, and ended up having survived in Captain America vol 7 #23.
The final issue of Captain America And the Mighty Avengers takes place just prior to the destruction of the Marvel Universe during Secret Wars. While several other characters are upset about dying, Luke Cage takes a very measured attitude and says that this likely isn't the end for real, just the start of a new chapter.
Ajak dies in "The Herod Factor" and returns in Eternals vol 3. Virako made a Heroic Sacrifice in Thor Annual #7, and returns in New Eternals #1. Zuras dies in Thor #300-301, returns, and dies in Iron Man Annual #6, and returns in Eternals vol 3.
Eventually, Neil Gaiman’s Eternals miniseries explained that they have complete Resurrective Immortality, although they’d forgotten this due to a Reality Warper.
Johnny Storm: Death is part of a journey and... and I know what I'm talking about here...death isn't the end. Of anything. Don't sweat this. We'll be back.
Guardians of the Galaxy: Drax, Phyla-Vell, Warlock/Magus, Nova, Star-Lord, and Thanos all died, but didn't die.
Great Lakes Avengers: Mr. Immortal is a parody of this. He's a Marvel Comics superhero with no special powers except immortality, who has been killed in ways including crushing, burning, self-impalement on giant novelty scissors, bear trap, cannon, chainsaw, piranhas, ferrets, spear, and python, and alcohol poisoning (three times).
General Ross died from fighting Zzzax, but his body was stolen by The Leader and resurrected by the Troyjan.
Betty Ross died of radiation poisoning, but she didn't really die. She washed up on a beach, was experimented on by Thaddeus Ross, became Red She-Hulk, lost her She-Hulk powers, got shot & died again and came back with her Harpy powers.
In issue #345, The Hulk is killed by a bomb from The Leader, in Middletown, and returns in issue #347.
The Leader is killed in an explosion in Incredible Hulk #400, returns as the leader of the Home Base organization, which never happened due to being part of a plot by Nightmare, shows up at a trial in She-Hulk, was killed by the Punisher, revived, killed again by the Punisher, which turned out to be an LMD, was given a permanent Penance Stare by Ghostrider, got sent to Hell by Mephisto, and is now fine.
Lampshaded endlessly in issues #397-#400. When a distraught Rick Jones goes to Doctor Strange so that he can resurrect his girlfriend Marlo, Strange explains how it's impossible. Rick goes on to point out how many other characters have died and come back, asking if Strange' assistant had (responding "Actually, yes"). It gets to the point where Marlo does get brought back to life by a magical priest and a crystal chamber simply called the "Deux Ex Machina." She comes back... but is left a complete shell from the experience. (She gets better before issue #418 [their wedding], though.)
And lampshaded again in another issue during Nick Fury's funeral, where his friends laugh and crack jokes, saying things like "What d'ya think it is this time, aliens?" By the end of the story they realize that he's not coming back, and look genuinely mournful. Of course, as we all know, he did come back anyway.
Someone even called Marvel out on their frequent use of comic book death in the letters pages of that very same issue, to which the response was "Okay, okay, we won't kill Nick Fur—Oops."
The Immortal Hulk series actually makes this a plot point, revealing that Gamma Beasts like the Hulk can cross a strange green door whenever they die, immediately bringing them back to life. For Banner, he's more than happy to just die, but a gallery of his previous deaths shows that one of his Hulk identities will just charge back through the door sooner or later. The Hulk dies several times throughout the series, and those each last for maybe an issue at most.
One story in She-Hulk's run had her move to have a dead man's ghost testify in his wrongful death case against the company he worked for. When the other side objected, Shulkie called Ben Grimm to testify about how he came back from the dead. When counsel objected the dead person in this case was an ordinary human and not a super-being, she then asked by a show of hands how many people in the courtroom had been resurrected from some cataclysmic event. About half the people in the room (including one of the other defense attorneys) raised their hand.
A "Legion of the Unliving" has been created by several villains in Marvel Comics, composed of those who had previously died. When it turns out those characters had been alive, the group members are usually considered to be clones or temporal copies.
In Alternate Universe story Marvel: The End, Thanos discovers that the universe is unraveling because of all the heroes coming back from death. He specifically blames things on Wonder Man, arguably the first resurrection in the Marvel Universe. Thanos then unmakes and remakes the universe, and states, "This time, dead is dead." Quite ironic in that Thanos himself has died some of the most times of any character, as he is literally in a relationship with Death.
Onslaught: The heroes die, but are really transported to a pocket dimension in Heroes Reborn, have strange adventures as their alternate selves, and return just fine in Heroes Return. Tony Stark died in The Crossing, replaced by Tony Stark of Earth-96020, who went to the Heroes Reborn pocket dimension and returned to Earth-616. Franklin Richards patches up Tony Stark's death by merging the version of Tony Stark of Earth-616 that Franklin Richards remembers, with Tony Stark of Earth-96020, who becomes a fading memory.
Frank died from an electric chair but didn't, became a zombie and got better, and then became a zombie and got better.
In Punisher Vol. 7 #5, The Hood resurrects sixteen C-List Fodder villains who had been killed by Scourge of the Underworld.
Two villains make major comebacks: the Russian (just as a head at first, the state he died in, then later with a Brawn Hilda female body. His head was revived thanks to stolen SHIELD tech, the body was an unavoidable part of the resurrection. He asks to have even bigger breasts), and Ma Gnucci actually a series of body doubles who accepted having losing all four limbs like Ma did, organized by a different villain.
Secret Invasion: The Wasp appeared to die, and was even later seen in the Underworld alongside other dead characters, but actually she was sent into the Microverse.
Once, when Spider-Man was asked if the villain of the day was dead, Spidey said "Probably. Half the guys I know have been dead once or twice. Usually did 'em a world of good."
Spider-Man himself got killed off three times for unrelated reasons over the course of a single decade. The first time in 2005's Spider-Man: The Other, when he gets killed by new villain Morlun. Peter stays dead for a single issue before his resurrection. He got killed again in 2012 in issue #700 of Amazing Spider-Manafter switching bodies with a dying Doc Ock. But then a relaunched Amazing Spider-Man series with Peter Parker debuting in April of 2014, around the time of the release of The Amazing Spider-Man 2, after being dead for a little more than a year. He then got killed by Deadpool (who was under the impression that Peter Parker was a Corrupt Corporate Executive) in Spider-Man/Deadpool, but after Deadpool realizes he was tricked, he calls in a favor from Death (his on-again, off-again girlfriend) to bring Peter back.
Jackson "Big Wheel" Weele appears to die in Amazing Spider-Man #183, but ends up surviving.
Aunt May dies in Amazing Spider-Man #400, but that was someone pretending to be her.
Norman Osborn kills Spider-Man once and for all in The Spectacular Spider-Man #263, revealed as a hallucination in Spider-Man #98.
Mary Jane dies in an exploding airplane in Amazing Spider-Man vol 2 #13, but she was really kidnapped.
Doctor Octopus was killed by Kaine in The Spectacular Spider-Man #221, and is later resurrected by the Hand.
Doctor Octopus died in Superior Spider Man, and had his consciousness transferred to the Living Brain in The Amazing Spider-Man vol 4. In just the slightest bit of a subversion, the original Otto Octavius really does die at the end of Superior Spider-Man , and the one that survives is an artificial copy made shortly before Otto's death. As such, the "resurrected" Otto lacks the memories of the original one's final days, including his Villainous Breakdown and Heel–Face Turn.
Hammerhead has been resurrected from a nuclear explosion, and survived a shot in the head with an adamantium bullet.
Norman Osborn and Harry Osborn died, but were really kept alive by the healing factor of the goblin formula.
Roderick Kingsley was considered dead, but had replacements take on the Hobgoblin identity while he retired.
Kraven the Hunter committed suicide in Kraven's Last Hunt, and is resurrected in Grim Hunt. He's not happy about it.
Mysterio committed suicide in Daredevil vol 2, shows up alive with a hole in his head, and is now fine, aside from being run over by Deadpool.
Carnage has survived death by sprouting new symbiotes, has survived being ripped apart by The Sentry in New Avengers, survived a deadly explosion by The Wizard, was suffocated to death and revived, and made a Heroic Sacrifice in AXIS and survived.
Eddie Brock appeared to commit suicide when the Venom symbiote went to Mac Gargan, but Brock was hospitalized, and survived.
Rhino and Silver Sable die in Amazing Spider-Man #687. In Amazing Spider-Man #690, Silver Sable is said to still be alive. Rhino shows up alive in Amazing Spider-Man Vol 4 #2.
Lampshaded with the death of Marla Jameson. Peter is so wracked with guilt over his failure to save her that he suffers a nightmare where he runs into her, and the following exchange occurs:
Marla: Don't worry, Peter. I'll be back. Peter: Wha? How? Marla: I used to build Spider-Slayers. That makes me a super villain. And super villains always come back.
Scarlet Spider: Kaine dies in Amazing Spider-Man #634-635, returns in Amazing Spider-Man #637, dies in Amazing Spider-Man Vol 3 #13, and returns in #15.
In Dead No More: The Clone Conspiracy, the Jackal tries convincing Spider-Man, the Rhino and the Lizard that their families and love interests can be brought back to life through cloning, but they will only return as clones, and clones aren't the real deal, unlike Ben Reilly, who died in The Clone Saga, and returns as the Jackal. What a twist.
During Mark Millar's Spider-Man run, Mary-Jane briefly mused that the mystery villain that had been ruining Peter's life might be Harry Osborn. When Peter pointed out that Harry had been dead for years, MJ retorted by saying that his dadused to be "dead" as well, and we all know how that worked out...
Lampshaded by Hammerhead in Ultimate Spider-Man. His first appearance ended with his skull being exploded by Gambit. When he returns a Mook remarks, "Geez, Hammer, I thought you were dead". Hammerhead responds with, "I was. It sucked. I came back".
This trope was seemingly subverted with Peter Parker from Ultimate Spider-Man, who was killed in battle with the Green Goblin, paving the way for Miles Morales. Peter not only returned from the dead, but if Norman Osborn is to be believed, he's now immortal.
Discused in Strange (2022). While talking about finding a way to resurrect Stephen, Wong complains that it's not as simple as Clea is making it out to be. Clea then asks how many of Stephen's superhero friends have returned from the dead. He replies, "All of them, it sometimes seems."
In Thor, Odin is killed by Mangog in #198, and revived by Hela in #201. Odin and the Asgardians die when their life-force is used in the Destroyer armor in #300; Thor revives them, with the help of the other pantheons, in #301. In vol. 2 #40, Odin dies battling Surtur, and is wiped from existence in the Ragnarok in Thor vol. 2 #85. The realms of Yggdrasil and its inhabitants, including the Asgardians, are destroyed, permanently, and gradually return in Thor vol. 3. Odin returns in Thor #618.
Given death in Thor generally just means "moves to Hel (or Valhalla)" it's generally even cheaper than in superhero comics in general. Up to one issue joking about the 9th death Thor that's undone in a pageturn.
Thunderbolts: Baron Zemo was beheaded by Nomad, and transferred his consciousness to a computer, and a new body.
The Ultimates (2015) has the Arc Words "Everything Lives", that ultimately imply that Death Is Cheap as a cosmic principle of the Marvel universe. This even applies to the universe itself. Six of the seven previous iterations of the universe arrive in the climax to save the current one from being assimilated by The First Firmament.
This is discussed in Valkyrie Jane Foster. In issue #7, Jane discovers Death on life support and the Grim Reaper explains that between the Green Door and the Krakoan resurrections, there really seems to be no need for a Death and requests she convince him otherwise. She does so by explaining that, without Death, everything would keep living on a cellular level, creating a Cancerverse.
What The—?!: In issue #25, Forbush Man dies, spoofing The Death of Superman, but the citizens are too apathetic to care. Forbush Man shows up in Nextwave, and returns to become a zombie in Captain America: Who Won't Wield the Shield.
Fittingly, this idea was mocked in the very same issue of Nextwave where Forbush Man came back:
Elsa: Didn't Tabby also say that Magik was dead?
Monica: Like that matters. X-Men come back more than Jesus.
Ariel died in X-Men: Legacy #235, and returned in X-Men: Legacy #259.
After Banshee dies, during X-Men: Deadly Genesis, his daughter, Siryn remains convinced it's a trick, pointing out all the other X-Men who have been reported dead, only to return. Her less savvy teammates believe she's in denial. When Banshee died, Siryn was in a different comic, X-Factor, and nobody thought to tell those writers that Banshee had been killed off, so she never responded to his death. When the writers finally found out, they decided, since Death Is Cheap, instead of trying to retcon her grieving in, to have her just be in denial. Eventually, she accepts his death. Banshee shows up in Hades, gambling to come back, returns and dies in Necrosha, and returns and dies again in Chaos War. In Uncanny Avengers, Banshee is back, but evil, and spends some time recovering. Also returning with him are Daken, who died in Uncanny X-Force #34, and The Sentry, who died during Siege. They are now just fine.
Blink died fighting Harvest in X-Men vol 2 #37, but really teleported herself and survived.
Colossus made a Heroic Sacrifice to stop the Legacy Virus. Then an alien warlord brought him back, swapped his body for someone else's, and used him as a lab rat for years.
Cyclops died, but his consciousness actually merged with Apocalypse. The two were separated, and Cyclops was fine. Then Apocalypse died once and for all when Cable pierced his astral form with his Psimitar, but it turned out Apocalypse knew how to regrow his own body in a vat.
Dazzler has died in Eve of Destruction, New Excalibur, and A-Force vol 2 #3, lampshading her deaths in issue #4.
Gateway died in X-Men vol 2 #202 and came back in Secret Warriors #4, but did not survive dying in Uncanny X-Force #27-28.
Depending on how you define "death" (depends on who you ask) Jean Grey has died anywhere from once to twenty times, possibly a record for Marvel. The first time was when she appears to die from solar radiation in X-Men #101, but is saved by the Phoenix Force. In The Dark Phoenix Saga, Jean appears to die by getting in the way of a laser cannon and saving Scott, but this was really the Dark Phoenix impersonating her. That was only the first two. Jean resurrects and dies multiple times in Phoenix Endsong, and seems to die for good at the end of New X-Men. A comprehensive list of her deaths is here. She stayed dead for a remarkably long 13 years (barring her younger self featuring in All-New X-Men), but ultimately returned to life in Phoenix Resurrection.
Laynia "Darkstar" Petrovna dies in New X-Men #130, returns and dies in Necrosha, has her essence passed around to two agents and a Dire Wraith, and is revived in Darkstar & the Winter Guard.
Magik died from the Legacy Virus in Uncanny X-Men #303, and returned by New X-Men #40.
Magneto died when Asteroid-M was destroyed in X-Men #3, but it turns out he did not die. Magneto died in New X-Men, but that wasn't Magneto. That was after he was presumed dead after the bombing of Genosha. In Uncanny X-Men Vol 4 #19, Magneto is killed by Psylocke and revived by Elixir.
Moira MacTaggert died from an attack by Mystique while researching the Legacy Virus, and returned from the underworld in Chaos War. Then it turns out that this wasn't even the real Moira, but rather a Shi'ar golem.
Mr. Sinister has returned from death by transferring his consciousness to a cloned body.
Nightcrawler died in X-Force Vol 3 #26, and returned in Amazing X-Men Vol 2 #5.
Psylocke was killed and stuffed by Vargas in X-Treme X-Men, and is now fine.
Professor Xavier died fighting Grotesk in X-Men #42, but that was really Changeling who impersonated him and died. Professor Xavier is erased from existence due to a Grandfather Paradox in Legion Quest, but survives. Professor Xavier survives being defeated as Onslaught. Professor Xavier is shot in the head in Messiah Complex, and survives. He does not survive Avengers vs. X-Men, but his brain survives and is used as part of Red Onslaught. In the Astonishing X-Men story "A Man Called X", Professor X returns in a new body, now calling himself X.
Wolverine died in Astonishing X-Men Vol. 2 #3, but that was a Skrull.
Doug Ramsey dies in Fall of the Mutants, and returns during Necrosha.
Warlock dies in X-Tinction Agenda, and returns in Excalibur #77-80.
Vanisher dies in New Mutants Vol 3 #13, and returns in Astonishing X-Men Vol 3 #48.
Old Man Logan is a Bad Future story set 50 years after most of the world's superheroes have been killed off. At one point, Wolverine and Hawkeye eventually come to Hammer Falls, a place where tourists pray for the resurrections of various superheroes. When Wolverine points out that the heroes aren't coming back, Hawkeye states that people still remember the old days, when heroes would die and then simply return with cool new costumes.
In Uncanny X-Men #325 Marrow has her heart torn out. She survives, due to having a second heart.
Sabretooth was beheaded by an enchanted sword, and then Wolverine fought and beheaded his soul in Hell, with a sword that does not allow a soul to be resurrected from Hell when cut. Then it turns out that was a clone and Sabretooth is just fine.
Cyber died when his flesh was eaten by scarab beetles. He returned when his astral form possessed a new body.
Wolverine dies in Death of Wolverine, and miraculously stays dead for a few years while alternate reality counterparts popped up. Ultimately played straight; as of Marvel Legacy, Logan's broken out of his adamantium cocoon and is back to the land of the living.
X-Factor: Jamie Madrox died from the legacy virus, and it was not one of his duplicates that died. But it turned out to be a duplicate that died. (Jamie later said he always keeps a few duplicates around for just such an emergency, making this something of an Author's Saving Throw for him). The exact same thing happened when he died from Terrigen poisoning, and it was specifically pointed out that both the original and all the duplicates were very much dead. Lo and behold, a little while later it turned out the original Jamie was just fine.
Pete Wisdom is killed in X-Force #103, but not really; then the whole team gets killed in #115, but not really.
Stryfe's body is destroyed in X-Cutioner's Song. His consciousness infects Cable, and is expelled to Blackheart's realm and defeated by Warpath. Stryfe returns and attacks Latveria, is killed by an explosion, returns and attacks the Xavier Institute, makes a Heroic Sacrifice to destroy the Bete Noir, and returns in Messiah War.
Boom-Boom was shot and killed in X-Force Vol 3 #13, but her death was prevented in X-Force Vol 3 #17.
Cable made a Heroic Sacrifice in X-Force vol 3 #28, and returned in Avengers: X- Sanction.
X-Man: Nate Grey became pure energy that dissipated across the surface of the Earth, and returned in Dark Reign.
Taken to its extreme in X-Men: The Krakoan Age. The mutants now have a reliable method for resurrecting their own in cloned bodies and with recent backups of their memories. So it takes on average about one issue for the recently killed characters to be brought back, and they are steadily working on the backlog of long-deceased mutants as well. A few mutants have been unable to be brought back for various plot reasons, but almost all of those eventually got resolved.
However, there's one big flaw the mutants learned the hard way: anyone who dies in Otherworld is dead forever as it is a nexus to the Multiverse and whoever gets brought back is an amalgam of other dead versions. Rockslide ends up being the unwitting guinea pig and Gorgon ends up killed in Otherworld as well.
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