Superpower Russian Roulette

Who wants to be a superhero? Everyone, duh...as long as he's not a superhero already, anyway. Kids who idolize them, teens desperate for a change in their lives, adults who think they could make the world a better place... and, of course, those with less savory motives.

For any of these people, the day they get caught in a Mass Super-Empowering Event and win the Superpower Lottery would probably be the happiest day of their lives. But sometimes a Mass Super Empowering Event isn't a lottery. Sometimes it's a deadly game of Russian Roulette, where only a handful of people affected walk away with superpowers — the rest become crippled, horribly deformed, killed, or worse.

The roulette has different kinds of ammunition to hit the contestants with, often they compound:

Examples of Superpower Russian Roulette include:

Anime and Manga

In Darker than Black, the appearance of Alien Sky divided those affected into two groups: Dolls, people transformed into Extreme Doormats with scrying abilities, and Contractors, super-powered sociopaths. If being emotionally inhibited and paying the price isn't enough, there are Contractors with some defect, Moratorium. They gradually turn into superpowered zombies on par with worst of mediums.
In Alive: The Final Evolution, one of two things happens to those affected by the force/virus involved in the series. Many people commit suicide immediately with disturbing cheerfulness, but some get superpowers (and typically end up as superpowered sociopaths)- the explanation is that they too desire death, but first are going to bring it on other people.
- The main characters also fall prone to those suicidal tendencies as well (especially early on in the series), but manage to fight back with The Power of Friendship.
Mermaid flesh in Mermaid Saga is a Superpower Russian Roulette with impossibly high risks. Most of the time, eating it will lead you to die horribly or turn into a grotesque, mindless monster, which sucks. Some of the time, you acquire some semblance of immortality, but with horrible pain and disfigurement to go along with it, which also sucks. If you're really lucky like the two protagonists, you'll actually get real immortality... Which, as it turns out, still kinda sucks.
In Rosario + Vampire, a human gaining powers from vampire blood runs a high risk of death or other unpleasantness. Touhou Fuhai's Human Modification Technique has similar, but even greater, risks. Tsukune goes through both.

Comic Books

In Strontium Dog, the strontium-90 fallout has a roughly 70% fatality rate. Women who get a mild enough dose end up giving birth to Mutants, but almost all of those babies just have various disfigurements or missing limbs. Only four characters actually end up with anything resembling powers, and one of those is a vampire.
The radiation in Judge Dredd works in much the same way. A few mutants get Psychic Powers, but 99.9% of them just end up looking weird.
Once in Incredible Hulk, the Leader (who is also gamma irradiated, but his power is a highly developed mind) set off a gamma bomb in a small city, in order to make more Hulks and Leaders, but 99.99% of the population just died of radiation poisoning.
Empowered has the drug "Mayfly," which kills you 98% of the time, but the other 2% of the time gives you super genius abilities. Then kills you in 48 hours anyway, but still.
- The only Mayfly used in the series, Manny, managed to use those super-genius abilities to survive past 48 hours. He's declined to do anything in person since then, as his body is basically a giant tumor at this point.
The Event in Milestone Comics (and its animated series Static Shock).
Grant Morrison's run on New X-Men had a particular focus on this aspect of the mutant gene. Sure, control over the weather and the ability to phase have few downsides, and while uncontrollable eye-beams and demonic teleportation powers have their draw-backs, it's nothing compared to the kids who have multiple noses or transparent skin made of wax or limbs so huge they can barely lift them. They're not able to aid a society that hates and fears them. They're barely able to get to class each day.
- That is also a good description for the Morlocks. Mutants who are horribly disfigured that have to live in the sewers.
- A Tear Jerker example is Minnie Floyd, whose aging slowed and reversed, eventually de-aging to the point where where the maternity ward's life support could not keep her alive. This "power" manifested at age 2.
- Another is a boy who wakes up one day to find he has the incredible mutant power to "destroy organic matter". Such as his parents. And his friends. And people he runs into on the street. Eventually, he wanders into a cave where Wolverine is waiting for him, who tells him what happened, and is there to help him. The kid tearfully notes that he might've been one chromosome away from being one of the X-Men.
Dial H for Hero is a one-person Superpower Russian Roulette. Whenever the dial is used, you don't know what you'll end up as.
- It later becomes a literal example when the Giant Boy got poisoned. Robby managed to turn back before dying, but he'll bite it for good if the dial ever transforms him into Giant Boy again.
Marvel Comics had The Inhumans who take a dip in a fountain when they're the right age in order to determine which superpower they get. Some come out with immense powers while others might have more mundane abilities.
The Savage Dragon works on this trope. Some "freaks" are planet-wise threats while others might have sillier powers such as Dung, who had the ability to shoot feces at people.
Norman Osborn sought power and took part in a ritual known as the Gathering of the Five along with Mattie Franklin, Morris Maxwell, Cassandra Webb, and Gregory Herd. Each person receives a gift of power, insanity, knowledge, immortality, or death, although no one knows what he or she will get beforehand. He believed he killed Spider-Man and thought he got he wanted. It was actually a delusion as he actually acquired the gift of madness.

Literature

In The Ear, the Eye and the Arm, most of the people exposed to the pollution developed harmful mutations: the title characters' abilities were a very rare result, and even they have some Weaksauce Weaknesses to go along with them.
Played particularly grimly in the Wild Cards series, where 90% of people who get the virus in question die horribly, 9% end up as Body Horror, and only 1% get the cool powers.
While Xanth is mostly Superpower Lottery there are people whose magic does seem to harm them, like Chameleon who has her looks and intelligence decreasing and increasing, The Dastard who has a magical gift for stupid ideas, or Zora who ages people.
In The Fall of Reach, the surgeries and processes used to turn normal humans into Spartans killed and crippled over half of them.
In Anne McCaffrey's Crystal Singer, the adjustment to Ballybran's symbiote follows more of a bell curve: a few die, a few attain the heightened senses needed to become a crystal singer, but most just end up with mild handicaps.
Whatever is causing the super powers in Gone (novel) is probably also connected to the reason why everyone over the age of 15 disappeared and the kids are now in a Domed Hometown. Also, the most likely reason is the nuclear fallout and the Gaiaphage. Overall, characters have gone insane, died, killed, been persecuted by the Human Crew, been tortured by Caine and Drake, and been horribly mutilated as a result of something changing the laws of physics. And of course most kids have really lame powers. Astrid can read people's potential or something like that, Duck can change his density, Bette could make her hands glow, an unnamed girl could go invisible only when she was very embarassed, Sam and Hunter started out with no control over their light/heat powers (with disastrous consequences), and Orc is now an Iron Woobie. Think you can avoid all this by not developing powers? Think again. Muggles are often overlooked in the FAYZ (Fallout Alley Youth Zone). Unless you're lucky enough to be Team Normal like Edilio, you are either a member of the Nazi-inspired Human Crew or a Red Shirt in an Anyone Can Die scenario.

Live-Action TV

Promicin injections in The 4400: Half of recipients get superpowers, the other half die.
Misfits is pretty much built around this concept. Most of the powers are downright Blessed with Suck, others are deconstructed to show their suckiness, and some aren't so much powers as curses.

Tabletop Games

Traveller Classic Double Adventure 3 Death Ship. The accidental release of a combination of experimental combat drugs aboard a science ship kills most of the crew but gives some of them superhumanly high ability scores and insanity.
In AD&D 2 psionic rules, eligible characters may try to discover random wild talents in themselves. The success is far from guaranteed, but this check has also 4/100 chance that Wisdom, Intelligence, Constitution or all three drops to 3 (minimum for a human being) instead.
- In First Edition AD&D, all psionic powered characters were basically "wild talents." If using the psionics rules (which were optional), all player characters had a tiny chance (on the order of a couple percent) to be psionic. Being psionic was a curse as well as a blessing, though, because non-psionic characters were immune to most psionic attack modes.
In one of the old D&D modules, one plane of existence basically causes this to magic. Some effects are truly beneficial like super strength or super senses. Some of them are deadly like spontaneously having your mouth and nose fuse to your face.
Happens in Warhammer 40,000, where turning to the worship of Chaos leads to one of two possible ends (unless you die first); you either get turned into a Daemon Prince, or you get turned into a mindless heap of mutated flesh.
- Also, all human psykers. The least powerful ones and the ones who can't control their powers are killed either by being "fed" to the devices sustaining the Emperor, or by being plugged into the Astronomican (although either of those fates results in having their soul sucked out, so it's practically the same thing). The most powerful and controlled get to be Grey Knights, Space Marine Librarians or Inquisitors. The ones who didn't get their souls sucked out but didn't quite meet requirements for the aforementioned positions usually explode, get possessed by demons, and/or get shot by a Commissar. And that's only if they're found by the Black Ships. If they aren't, then at some point the demons will use them to rip a hole in reality and kill everything on their planet. If the Inquisition doesn't find and kill them first, that is.
Self-applied in Die or Fly superhero settings, such as Aberrant or Paragons. Given the sheer power, and the celebrity associated with such power, there are quite a few people who take suicidal risks to try and trigger their powers. This rarely works... but when it does work, it only draws more attention to the process...
Geist: The Sin Eaters has a passing mention of one of the Dead Conspiracies, the Vodyanoy. Apparently, Soviet scientists found out about the process of becoming a Sin-Eater and subjected political prisoners to experiments in inducing hypothermia and drowning in order to see who'd come back from their near-death experience with superpowers, even though the success rate was maybe .5%. And then they found out why it's a bad idea to use political prisoners in inhumane experiments that might end up giving them superpowers...
Big Eyes, Small Mouth (and by extension Tri-Stat dX) has the Unknown Superhuman Power advantage. It means you give the Game Master carte blanche to choose whatever advantages s/he wants and reveal them to you over time, but to make up for the loss of choice you receive a 50% bonus to whatever you put into USP (meaning if you pay 10 Character Points, the GM has 15 to spend).

Toys

Energized Protodermis in Bionicle. Take a dip in it, and you might get enhanced superpowers... or transform into a hideous monster... although, odds are, you'll just end up getting destroyed if it wasn't your destiny to transform.

Video Games

Appears at first to be in effect in the game Prototype, where most people infected by The Virus turn into zombies while protagonist Alex Mercer becomes a Person of Mass Destruction with shapeshifting powers. It turns out that the real Alex Mercer was killed when he intentionally released the virus. The virus itself then took his form and memories — and another path entirely.
- Although there are two seperate strains of The Virus; Redlight (which is behind the zombies and is controlled by Elizabeth Greene) and Blacklight (which is, according to Mercer, ten times as lethal, and outright killed everyone in Penn Station).
This also happens during In Famous to kick off the start of the game. The Ray Sphere empowers a few lucky "conduits", and everyone else within a few city blocks of blast dies in order to fuel those super powers. Using it again to further supercharge your own abilities will drive you permanently across the Moral Event Horizon later on in the game.
The case in Mass Effect with element zero and biotic powers. Most people exposed to element zero at a young age die of brain tumors...a few get the ability to warp space with their minds.
This is also the case in Dragon Age Origins with the Grey Wardens' Joining ritual. The prospective Wardens must willingly expose themselves to a special version of the Darkspawn Taint by drinking a mixture of Darkspawn blood, lyrium, and Archdemon blood. Many of the candidates immediately die horribly after drinking it. The survivors...aren't much better off in the long run.
Wesker virus in Resident Evil. Gives you super strength, reflexes, speed, and regeneration, while not affecting your appearance, intelligence and personality, with the only visible effect being Red Eyes, Take Warning cat-like eyes - if you survive, which is VERY unlikely.
- Uroboros also is supposed to work this way, but success results just in not as severe Body Horror as the failure does.
  - It's actually implied that Wesker's mutation by Uroboros is also a failure, altered in some way by the previous virus being present in his body. The one time where a definite success is noted is with the Reapers, six-foot tall cock roaches with four of their legs turned into spear-like appendages capable of stabbing through a grown human with ease, and a ridiculous Healing Factor, capable of regenerating everything from a lost limb to a disintegrated head within seconds. The only thing capable of killing them is a few well-placed shots in their weak points which they rarely deem to reveal, or a direct hit with a rocket launcher.
Mutation in Dungeon Crawl. You can get cool stuff like permanent stat increases, intrinsic resistances, complete immunity to poison or mental effects, breath weapons, increases to maximum HP or MP, or scales that raise your armor class. You can also get permanent stat loss, intermittent temporary stat damage, start constantly screaming and attracting attention from all nearby monsters, or become too warped to fit into your armor.
The FEV (Forced Evolutionary Virus) in the Fallout series fits this trope. Exposure to the FEV can do a range of things to a human though there is always a downside to the effects, very often a severe one. For starters it can simply turn somebody into a gigantic mass of disgusting flesh. And then it can also turn somebody into a Super Mutant. If turned into a Super Mutant sterility is guarunteed and insanity is common, however, technical immortality and incredibly enhanced physical strength can make up for this. There is also an incredibly high chance that a Super Mutant will be rather unintelligent, though occasionally a mutant of normal human intelligence will be produced, and even possibly one of superior intellect.

Western Animation

Pretty much the whole premise of Generator Rex. Thanks to the whole world having been seeded with nanites, anyone at any time could mutate into an EVO. While some EVOs just get superpowers (like the title character), the vast majority get turned into mindless monsters- and of those who do maintain control of themselves, only about three in the whole show can pass for normal human (Rex, Circe, and Van Kleiss). And if you're an intelligent and obvious EVO, expect lots of Fantastic Racism. Fun, right?
- Even if you manage to avoid becoming a mindless monster, you're still quite likely to end up Blessed with Suck. Van Kleiss is a humanoid abomination that must consume the nanites of other evos to survive, Circe is a Weirdness Magnet, and Rex's Phlebotinum Overload is pure Body Horror. Then there's people like Breach who have awesome powers at the expense of their minds.
  - It goes beyond that even! It has been revealed so far that Rex, in addition to all the Wonderful side affects of his powers has a chronic condition that periodically gives him Laser-Guided Amnesia and, along with the Body Horror, a Super-Powered Evil Side in the form of a Humongous Mecha thing as a consequence of a critical Phlebotinum Overload.

Real Life

Autism. 1 in ~150 people are born with it. Of them, most require extra support throughout childhood to develop somewhat normally in social matters, and only a few will ever "recover" and lead a normal life. For a scant few, things will click just right in their mind to turn them into a "Savant," a real-life version of a TV Genius, though typically only in a very limited range of subjects (most commonly math and music).
- And being a Savant is almost always being Blessed with Suck. Roughly half are autistic. Most of the rest have a serious psychiatric issue. A very small few escape the developmental disabilities, who are usually known as prodigies.