"I just want a normal life."
"My friend, you will have as many of those as you wish."
A Perpetual is a person of the grim darkness of the 41st millennium who drew the absolutely shortest straw possible: they are immortal. And nothing of this "age without youth" or "immortality without indestructibility" bullshit: they do not age and can survive the most gruesome deaths imaginable up to and including taking an Exterminatus to the face because they can reassemble themselves from their constituent atoms. They're like Wolverine on steroids like that. Which, given the relentless sunshine of the Warhammer 40.000 universe is NOT a good thing: not even death will relieve your suffering. There are only a few things said to be able to kill a Perpetual for good, but these powers and weapons are known to only a few individuals in the galaxy (and even then it's not known for certain how effective they are, or if they even work). Very little is known about the Perpetuals including their origin (but given the fact that Ollanius Persson was around as far back as the time of Greek myth, they've undoubtedly been around for ages), number, purpose or even if those suspected to be them actually being Perpetuals (all that we know is that during the Horus Heresy, there were exactly 3 Perpetuals living in Ultramar; given that Ultramar consisted of 500 planets at the time, we have to assume that they're extraordinarily rare). Of only eight individuals is the status of Perpetual known or confirmed. Another foible they have is their very existence fucks up farseeing to a considerable degree, which lead Eldrad to kill off as many of them as possible to try and find a way to avoid Chaos winning overall.
We do however know, that people could be turned Perpetual by being resurrected. Which, ironically, might imply that Kharn and Lucius at some point became Perpetual too, since they've both came back from dead. It'll explain how Kharn managed to survive for that long despite his suicidal psychotic charges into everything he sees, and how Lucius resurrected without possessing anyone's body after first being outfought by Nykona Sharrowkyn of the Raven Guard, and then subsequently being cut to pieces by an emotionless Rubric Swordmaster (who in any case no longer had a body to possess either).
Recent fluff has revealed that the universe itself (or is it just the Eldar? Assholes that they are.) isn't too keen on Perpetuals as their very existence is a spanner in its gears, because
people should die when they are killed each of their revivals end up fucking farseeing over and altering causality. In order to try and find alternatives to the Cabal's plan of letting humanity die to kill Chaos, Eldrad went on a galaxy wide murder tour bumping off other Perpetuals and members of the Cabal, a choice he deeply regretted when he tried farseeing and saw what the future would eventually hold. It also turns out they're capable of resisting daemonic possession, partly due to any warp entity inhabiting their soul gets fucked up when they die (and then come back). It's still implied to horrifically traumatic but it explains how both Alivia Sureka and Anval Thrawn were able to resist.
Predating the Great Crusade
With all of his mysteries about the Emperor it would explain a number of things if he was a Perpetual: such as his age, knowledge in an era where everyone else on Terra was too busy LARPing a crossover of Terminator and Fist of the North Star to learn shit and his massive power (learned over time). On the other hand it would not explain why he didn't just regenerate after being bitchslapped by Horus. The best explanation for this (besides Horus being able to injure the Emperor permanently through being the virtual avatar of all four Chaos Gods) is that that the Golden Throne, while maintaining his life functions, is also keeping him from resurrecting himself- in theory, if it was shut down, the only real effect it would have is that the Emperor would "die" for a day or two at most before fully healing from his injuries. A shame that nobody seems to realize this, as it would end most of the Imperium's problems on the spot at the expense of leaving Terra defenseless to being raped, both literally and figuratively, by hordes upon hordes of daemons, even if for a couple days. (That's assuming he doesn't turn into a real God the moment he "dies" and use his new God-like powers to seal the broken portal). Though it would create some new problems, as quite a few people wouldn't be happy with the return of Imperial Truth, especially the Ecclesiarchy. Of course, knowing the Emperor he'd crush them like bugs if they tried to oppose him, or even if they didn't. There is no way he would agree with the current Imperium.
Recent revelations from the Horus Heresy books also suggest that his godlike powers were actually stolen from the Chaos Gods themselves instead of being wholly his own. Needless to say, the Ruinous Powers still have a grudge.
- Note: This is what Chaos Gods told Horus (since the initial Horus Heresy trilogy, though Vengeful Spirit had them stick with the story), and we all know how trustworthy they are. The most plausible explanation is that Emperor either tried to destroy them but failed or he infiltrated their compound to learn the secrets of the warp so he could divide fragments of his souls and make Primarchs from them. Or possibly, the original "gods" in the portal may also have been referring to Eldar pantheon (or what remains of it), who may have given the Emperor his powers, and possibly an easy way back home (via the webway) since the Emperor didn't need a ship to get back home.
Ollanius Pius, AKA Ollie Persson
A confirmed Perpetual. By the time of the Horus Heresy, Ollanius reckons his age to be around 45,000 (give or take) and he is fully aware of the connection between the Imperial and the Gregorian calendars, putting his birth at around 15,000BC (or in layman's terms, somewhere in the latter half of the Stone Age) in Biblical Nineveh. Ollie Persson is quite reasonably older than the Emperor, considering that big Emps was born in Anatolia around 8000BC. At some point in time he became a Christian, and maintained his faith until, well, forever. Even once the word "Catholic" was somehow was corrupted in to "Catheric." As taught by his by-then-ancient faith (cf. Romans xiv, 3ff., referring to the Emperor of the time ... plus ça change, no?) he was a faithful Imperial citizen and, while the Imperium forbade religiosity, it did not (at the time of the Horus Heresy, which is when we last hear of Ollie) require worship, which would have given any troubles to his religious scruples, even if they were proscribed by the Imperium (again, nothing new for the Church.) Despite the prohibition on religion, he seemed to live his faith reasonably openly and at best be regarded as a bit of an eccentric for it: again, not all that different from certain eras of the Roman history in the 2nd and 3rd centuries.
He was one of the Argonauts of Greek myth and fought at Austerlitz (described as Napoleon's greatest victory) and Verdun (infamous as one of the bloodiest battles in all of World War I, which is saying something), as well as the First Gulf War, implied to have been fighting on the side of Suddam Hussein (in fact, the vague hints we get about his military history, which is extensive—having been apparently a soldier in all his documented lives, if not all of them, period—it's also implied that he tends to fight on the losing side, or even exclusively has, whether as some sort of curse or by some sort of design.) It also explains how he managed to survive boarding Horus' flagship during the Siege of Terra. It is unknown if Horus actually managed to kill him: while CHAOS MINDBULLETS certainly sound like they could do the trick it still is quite possible that he reassembled himself and walked off, not giving a fuck. A man with true balls of steel, especially as it's implied that he's never died once in his whole lifetime, and most of the time he has come back and back again to fight wars in the (literal at times) trenches. He does not want to be bothered one single fuck with John Grammaticus or the Cabal, but gets suckered in to galaxy saving adventures once and again. Such is the lot of a perpetual.
St. Ollanius Pius: Old Lore and New
Before perpetuals were introduced in the Horus Heresy novels, specifically in Legion by Dan Abnett, and more on Ollanius is elaborated in the some particularly good stories by Abnett set on Calth stories, especially Know no Fear and Unmarked (a short story anthologized in The Mark of Calth), St. Ollanius Pius was just a regular old balls-of-steel Guardsman who's balls turned to adamantium as he threw himself in front of his emperor during the most epic duel of all time, and thus was sanctified in lore and the Imperial cult from then on down. He was later revealed to be a Perpetual somewhat controversial change. From the point of view of the average Imperial citizen, or indeed, in fact just about anyone perhaps save the Emperor himself, he was that adamantium-testicled Guardsman and remains that holy Saint who is highly revered by the Imperium (the highest decoration in the Imperial Guard, for instance, is named for him.) In fact, of course, he may still wandering around, probably from what we all know trying to live this all down modestly. Ollanius, no doubt, would prefer the ambiguity as to whether his existence was utterly obliterated in the horrendous space kablooie surrounding the duel between the Emperor to remain as such.
Former officer of the Emperor's armies during the Unification Wars on Terra and later agent of the Cabal and a lesser psyker; John Grammaticus
WHO WAS GORDON GRAMMATICUS' BROTHER WAS ONE DAY AT AN OFFICE TYPING ON A COMPUTOR is an interesting case: after he died at Anatol Hive an Eldar Autarch called Slau Dha found his body and made him into a Perpetual, signaling that it is possible for humans to become Perpetuals. That, or Slau Dha was the equivalent of Ramirez and John was Connor MacLeod from Highlander. If this were the case this would make John and Slau Dha at least eight times more awesome. Grammaticus' skills gained over the course of a millennium of life were instrumental for recruiting Alpharius to the cause of the Cabal, but he felt bad for this and stepped out of an airlock in the faint hope that it would kill him. (It did, but then he just came back to life again). After the Drop Site Massacre he spent some time digging up an old relic spear that was actually made from cast-off lightning of the Emperor's divinity, reputed to be able to kill anything, even other immortals. After the apparent failure of the "Alpharius Gambit" (two choices, two primarchs, go figure) the Cabal had intended to use it to stop Vulkan from reaching Terra and interfering with their future plans. Unfortunately such a powerful relic made Grammaticus into a big giant target, and he ended up getting captured, killed and recaptured by the Word Bearers and the broken legions and eventually finding his way to Macragge.
On the way he was contacted psychically by this dick who told him that he could strike back at the Cabal by stabbing Vulkan himself, since if another immortal did it it would work differently, and in this case it would somehow heal the primarch who was mentally broken after years of torture by Konrad Curze. Because of reasons. So after seeking Vulkan out on Macragge he stabbed him, investing his own immortality into the strike, and sucking it out of himself and making him mortal... also apparently killing Vulkan properly this time and therefore doing what the Cabal wanted in the first place. Also at some point during the invasion of Calth he found Oll Persson and tried to recruit him to the cause, though that didn't go too well as he was only half-hearted in his attempts anyway, plus Oll couldn't be bothered. He was mindwiped after the Vulkan thing, but Eldrad restored his memories and asked him to make sure Oll reached Terra.
Alex Krycek in space. Another agent of the Cabal, though unlike John Grammaticus, Damon was more of a soldier than a spy and got all the killy jobs. It is heavily implied that he was the one who killed Martin Luther King Jr. and Robert F. Kennedy, as well as other important figures throughout human history. No, really. The novels specifically mention he was responsible for the death of "the good man in Memphis" and "the brother in the City of Angels".
Was apparently more comfortable with his position in the Cabal, even though it meant working against his own species, and would infer as much during his meetings with John Grammaticus, which made him more trustworthy in the eyes of the Cabal. During John's last mission Damon was sent to watch over him and make sure that he didn't falter or chicken out and try to derail their plans. Though he sort of failed to contain Grammaticus, he does kill Vulkan once, shredding him with a pair of shuriken pistols, but it's worth noting the primarch was already pretty shattered after having died a couple of times by that point.
He was the individual who brought Cyrene Valantion into the Cabal's fold, having to die once or twice on board the Word Bearers' starship just to prove a point to her. He's now definitely dead for real after Narek shot him in the head with a fulgurite round at point blank.
Another female Perpetual and empathic psyker and the most recent to be introduced. Unlike most of the others though she has no apparent connection to the Cabal at all, and in fact is much more closely linked to the Emperor. She had traveled with Him and undisclosed "others" to the planet Moloch where the Emperor somehow travelled directly into the Warp and stole portions of the Chaos God's powers (or so the Chaos Gods claim).
She was left behind on Molech to guard the gateway to stop anyone else from passing through and doing the same thing. Which apparently she did dutifully for a few thousand years... meaning that she is the only other Perpetual in the Emperor's peer group who is actually loyal to him at the time of the Crusade. When the Great Crusade arrived on the planet, the Emperor fortified the shit out of it, leaving detachments of Blood Angels, Ultramarines, Imperial Knights, Titans and Imperial Army, making her somewhat redundant so she settled down and married. At least until Horus arrived during the Heresy and laid waste to most of the Imperial forces in a bid to follow in his father's footsteps and take the same power for himself.
Humorously, Alivia has several affectations brought over from the third millenium; she has a tendency to use "modern-day" phrases such as "OK", which do not actually exist in the 31st millenium. She also carries around a book of Hans Christian Andersen stories (probably one of the most priceless artifacts in the Imperium, if anyone knew what it was) which she reads to her adopted children.
Surfaced during and after the Great Crusade
Like his dad probably was, Vulkan of the Salamanders was a confirmed Perpetual. This was put to the ultimate test by none other than
the goddamn Night Haunter himself the little emo goth kid on super-steroids, who proceeded to perform the most depraved tortures and murders on the Lord of the Salamanders in an attempt to break his will, and had to invent several new ones just for the occasion. Whether he was shot with bolters at point-blank range, cut apart, decapitated, eviscerated, impaled, dismembered, evaporated, getting his throat torn out with a rusty fork, being quite literally mindfucked, or being tossed naked into an active warp drive, Vulkan would neither break nor stay dead, pissing Curze right the fuck off. Eventually, Curze locked him in a maze courtesy of Perturabo where he would hunt Vulkan himself. Curze's mistake was to place Dawnbringer at the center of the maze. When Vulkan got to his hammer, he proceeded to hand Kurze a helping of it straight to the face, then he activated a built-in teleporter that sent him right over to Macragge where he promptly burned up in the atmosphere like a human meteor, killing him again in the process.
Here things get complicated: Vulkan regenerated on Macragge but lost his mind, so Guilliman kept him locked up until he could figure out what to do with him (even concealing his presence when the Lion arrived). However, when Konrad Curze arrived on Macragge after stowing away on the Lion's flagship, Vulkan escaped in a moment of lucidity and tore his way across the planet (while naked) hunting Curze down and almost defeated him in a one-on-one duel. Shortly afterwards John Grammaticus found the broken primarch and stabbed him with the fulgurite, a stone spearhead charged with the psychic essence of the Emperor himself. He could not regenerate from this and neither Roboute Guilliman, Sanguinius, nor Lion El'Jonson could remove the spear from their brother's chest. Given that he was sent back to Nocturne for burial, we are forced to assume that his casket included a long tube-shaped appendage at least several feet long sticking out at an unusual angle, making this (while tragic) at least eight times more amusing (assuming that he was ever stabbed in the first place[though it was only the head of a spear not the shaft itself]).
Guilliman was hopeful that Vulkan would resurrect himself in time and insisted that the coffin was a preservation capsule, which Guilliman dubbed "The Unbound Flame". Some Salamanders who maintained a vigil of mourning thought they could hear a heartbeat. After an even more convoluted series of events surrounding the return of Vulkan's remains to Nocturne, the Primarch was found alive and well once more, which is even more confusing given that the fulgurite, which was supposed to kill him permanently, was still sticking out of his chest at the time of his entombment.
What raises an interesting question in Vulkan's case is regarding the source of his powers. If it was given to him by the Emperor, it begs the question why the Emperor did not give all of his sons this ability (though it sort of answers itself with the thought of Angron becoming the Juggernaut (bitch!). If it was not the case, it would suggest that the Perpetual trait can be passed down one's bloodline, or at least transferred by cloning. Big E certainly knew that Vulkan was immortal and depended on that fact in order to get him to bring the Talisman of Seven Hammers back to Terra. This couldn't have been the Emperor's "ultimate plan" for Vulkan, and seems more of a last ditch contingency considering how badly the Golden Throne got fucked over by Magnus; if he had planned to put a self-destruct on it all along, he probably could/should have done it before he got stuck sitting on it.
The Emperor also told Vulkan plainly that his son's "humanity" was his single greatest trait and also his proudest achievement, and that he hoped that Vulkan would eventually teach it to his brothers. Certainly Vulkan was probably the nicest of the Primarchs and as such would probably have been the best bet for an undying son, especially if you were relying on him to tone down the more extreme traits of his brothers after the Great Crusade was finished. When Empy was looking over the petri dishes for which one to add the immortality to he had to choose between (in order): a two faced jerk, a [RECORDS LOST], a preening egotistical asshole, a genocidal maniac with poor impulse control, Genghis Khan, a dick with a furry fetish, a stubborn joyless masochist, a psychopath serial killer who uses terror as a weapon, a guy with a terrible terrible secret, a nerd who'd rather be talking to a toaster, a [RECORDS LOST], an explosively violent psychopath, a jerk with a heart of gold, an aspie psychopath, a massively powerful arrogant psyker who can't take orders, a spoiled egomaniac, a petulant child with a religiously pathologic daddy complex, an emo bird, and two people obsessed with secrets and lies. On the other hand, a lot of those traits were nurture rather then purely nature. Even so, if he did do it deliberately, he made a decent choice.
Justicar Anval Thawn of the Grey Knights is the biggest mystery of them all. All that is known is that he can walk away from the most gruesome Daemon-inflicted deaths one can imagine, much to the chagrin of his brothers and bewilderment of the Brotherhood's Librarians. It also begs the question of why him being a Perpetual was not detected during his induction into the Grey Knights, either during the tests or abnormal recovery from the involved surgeries or the speed at which he accepted the nineteen organs. Perhaps the Perpetualness is undetectable by normal science or it manifests after a person's first death (much like in Highlander or the Planeswalker spark of Magic: The Gathering). Another option is that he might be Ollanius Pius or John Grammaticus, who were tired of dicking around for another 10.000 years and wanted a shot at becoming a Space Marine. And an even better question is how the fuck the Eldar were able to recognize him for what he was after only a short period of interaction with them.
Cyrene Valantion was a common woman from Monarchia, a planet conquered by Word Bearers during the Great Crusade, until the Ultramarines blew her home city to ashes to send a "Stop Worshipping Me!" message from the Big E to Lorgar. Since the smurfs weren't complete assholes they evacuated all civilians first (only BLAMing those who didn't want to in process). Well, except Cyrene and a couple (hundreds) of others. She decided to stay out of the city borders and watch as orbital bombardment erased her home. Apparently watching an entire city being nuked was not her best decision, since she lost her eyes and almost died due to the extreme flash of light and from radiation burns. When the Word Bearers arrived they rescued her and figured that she was the only surviving witness of their punishment, because smurfs couldn't be bothered helping civilians whose city they just destroyed. This turned her into some kind of saint in their eyes, so they offered her a position of Confessor/Holy Relic, aka "The Blessed Lady" in their fleet. During the few decades of her service to the Word Bearers she became on a short hand with captain Argel Tal and guided him to his path to become the first Possessed Marine and overall awesome guy who kill loyalists and isn't afraid anything. Everything was fine and dandy until the Heresy, when during the Drop Site Massacre she got herself killed by some Custodes assholes
for just being in their way who thought they'd have an easier way obtaining answers out of her than from any Word Bearer. Needless to say Argel Tal cried manly tears of rage over her corpse and swore revenge at Custodes, which he delivered just a few hours later, butchering them all amidst the ashes of Istvaan V.
Fast forward one year to Erebus being a dick where he resurrects her to facilitate his machinations with Argel Tal. Mind you while she was dead for a year, he had her soul torn apart and eaten by multiple daemons from whom Erebus "persuaded" to give the pieces back. Being the badass she was, Cyrene recovered from the shock of being mutilated and tormented in hell surprisingly fast, until the battle for Nuceria, wherein her ship was blown up and she got rescued by none other than Damon Prytanis who told her that being resurrected turned her into Perpetual. And then... cliffhanger.