Say you have a character hosed with enough radiation to turn a person into a carbon shadow on a wall. This being a Comic Book or Sci-Fi story, odds are it turned them into a Mutant, Zombie, mutant-zombie or just plain gave them superpowers. The other upside? Radiation is now nearly harmless to them.
Much like a (highly accelerated) version of how some food tasters slowly build up tolerance to poisons, characters who survive exposure to deadly amounts of radiation usually also adapt a resistance to it... heck, they may even start absorbing it and using it as their Power Source. It may also result in Feed It with Fire and trigger a Healing Factor, Hyperactive Metabolism, or the like.
Sometimes they develop a dependence on the radiation, and need to live in (or make trips to) radioactive places or die. Alternately, they may start to generate the radiation themselves note as a kind of organic atomic reactor, and they might not be able to contain it. It may be possible for this immunity to be overcome with sufficiently overwhelming radiation sources.
- It's not certain whether Tomie is a mutant or demon or something else entirely, but she is known to be extremely radiotrophic. In an early manga story some doctors try to kill her with a radiotherapy machine, but this only accelerates her Healing Factor. This also gives a neat justification for the whole Shapeshifter Baggage problem, since presumably under normal circumstances her (usually painfully slow) regenerations are fueled by background radiation.
- The Incredible Hulk and his gamma-radiation-empowered Rogues Gallery have a higher resistance to radiation because of their mutations. In fact, The Hulk even emits gamma radiation as part of his transformation. In particular, Red Hulk gains power not from rage, but from absorbing radiation.
- Captain Atom's origin story has him worse than mutated — his body is vaporized by an atomic blast while inside an alien space ship. His soul/mind somehow manages to bond itself to an alien metal alloy, turning him into an Energy Being inside a Chrome Champion metallic shell. This transformation renders him effectively immune to radiation and able to manipulate energy. In a bit of a reversal, while the metal skin is tough and does protect him from radiation, it also protects everyone else from him suffering a Superpower Meltdown or generally irradiating everything.
- Played with and taken to further extremes than Captain Atom in Watchmen, where Dr. Manhattan is blasted into his component particles in a Freak Lab Accident, after which his disembodied consciousness gains a sort of Enlightenment Superpowers and forms a new body through reality warping. This is played for drama when his ex wife reveals she got cancer from him. She was actually secretly exposed to radiation sources by the Big Bad just to make Dr. Manhattan start avoiding humanity. This is actually just a peripheral ability for his general immunity to all damage, including disintegration.
- In Fallout: Equestria, ghouls and other creatures that survived the original nuclear fallout, such as phoenixes are resistant and even heal in the presence of radiation. By the end, Littlepip gets the same benefit, even though she can still get radiation sickness.
- In The Bridge, Godzilla Junior and Xenilla are this as per their mutations into kaiju. However it's found normal Equestrians are this as well naturally due to living in a realm with so much free flowing magic that races have magical abilities biologically. Means that thankfully being around Junior or Xenilla won't give them radiation sickness.
- X-Men Film Series
- In X-Men, Magneto's machine triggers mutation in normal humans but has no effect on mutants. Somewhat Justified in that it's implied to activate the dormant X-factor gene —in mutants said gene is already active.
- X-Men: First Class is a subversion, however. Despite delivering the page quote, Sebastian Shaw has no evidence that any mutant other than himself would be unharmed by nuclear radiation. It's possible that this is part of why Magneto took several additional decades to work on his own plan, despite agreeing with Shaw's goals.
- Subverted with Big G himself. While absorbing radiation does make him larger/stronger, he can also go into a nuclear meltdown if he absorbs too much radiation, as seen in Godzilla vs. Destoroyah.
- A subversion in Godzilla (2014). The Mutos are immune to radiation (and feed on it!) but are actually natural creatures, originally from a time when radiation levels on earth were much higher.
- In the Noon Universe, the Golovans (sentient canine species) evolved from common dogs on the irradiated post-nuclear war wastelands of Saraksh and are largely immune to radiation. But then again, so are humans from Earth (though not the Human Aliens of Saraksh itself).
- Subverted in Isaac Asimov's story "A Pebble in the Sky", Earth has become radioactive and the humans still there are slightly more resistant to radiation than the rest of the Galactic Empire, but it's not statistically significant. However they are resistant to radiation-mutated diseases that are lethal to off-worlders.
- In the original, ORIGINAL debut of the Daleks in Doctor Who, they were the mutated descendants of a people exposed to too much radiation (hiding inside pepper-shaker shaped travel machines). Turns out, they didn't need to worry about the radiation and would actually die if the rads were turned off. This dependence on radiation was retconned or ignored entirely in every subsequent appearance by them.
- In The 4400, those who've gained superpowers from exposure to Promycin become immune to it. Normally though, exposure has a 50% chance of death.
- In The 100, the Grounders (descendants of people who survived the nuclear war) and people from the Ark (who have survived exposure to high radiation levels in their orbital habitat) can endure the current levels of radioactivity on Earth's surface. The Mountain Men (descendants of people who took shelter in the Mount Weather facility) aren't so fortunate.
- Mostly averted in Gamma World. A mutant could have a power that protected against radiation (e.g. Physical Reflection-Radiation), but most mutants had no more resistance against radiation than non-mutants.
- Champions, Adventurer's Club magazine #2 adventure "What Rough Beast!". A GENOCIDE laboratory mutates a bear into a monster that needs a continuous supply of radiation to maintain its special abilities. It is, of course, immune to damage from radiation. The PCs can most easily defeat it by shutting down the laboratory's malfunctioning nuclear reactor, which is releasing a high level of radioactivity.
- Ghouls in the Fallout series are both immune to and heal from radiation. However, radiation also tends to turn ghouls feral. Glowing Ones, an especially rare kind of ghoul, are walking fallout zones that can create "bursts" of radiation that harm the player and heal nearby ghouls. Super Mutants, products of the Forced Evolutionary Virus, also appear to be immune or highly resistant to radiation, though they don't feed off of it like the ghouls do note . There are also perks that give the Player Character certain benefits from radiation poisoning, though they generally don't make you immune to it.
- In Command & Conquer games, tiberium-induced mutants (from visceroids to partially mutated humans to cybords made from harvested mutant body parts) are not only unharmed by tiberium radiation and dust/spores, they're outright healed by it.
- Warcraft III: the Undead faction have the Disease Cloud ability, which allows Meat Wagons and Abominations to deal additional damage over time via persistent clouds of noxious plague to their targets, which the undead are immune to (even the enemy).
- In Civilization: Beyond Earth, the there are plenty of poisonous gases on the planet that will kill an unprotected human. A faction following the Harmony path can eventually learn to heal in the gas.
- Downplayed in Pokémon Uranium; Nuclear type Pokemon aren't immune to Nuclear type attacks, but they do resist them, which is still notable considering they're weak to everything else (not accounting for second types and their match-ups).
- Peabody, an Albino Deathclaw from Deathclaw Desu Ga, absorbs radiation with no ill effects. Her Pip-Boy states that "You should be dead from Radiation Poisoning." However, being an albino, she sunburns within an instant.
- In Captain Planet and the Planeteers, the eco-villian Duke Nukem (not that one) loves radiation so much that he turned himself into a mutant. He even bathed in nuclear radiation as a mutant in one episode without ill side effects.
- Mutants in Futurama are immune to the effects of the mutagenic lake that spawned them. Leela is revealed to be a mutant when she is dropped in the lake and comes out unaltered.
- Mighty Max had an episode where a scientist tried to irradiate the entire Earth, because after an accident, he couldn't live without high radiation levels.
- Subverted in Teenage Mutant Ninja Turtles (2012); in the second episode when the Turtles obtain a canister of the Kraang's mutagen, Mikey tries to drink some of it assuming that a second dose will make a mutant mutate further. He's proven right in season 2 when Dogpound falls into Baxter Stockman's mutagen vat and turns into Rahzar.
- There is a bacterium, Deinococcus radiodurans, that can survive radiation, among a large number of other environmental stresses. It was discovered when food preservation scientists thought that irradiating canned goods would destroy every organism inside it, but found this creature alive and breeding. It can withstand up to 5000 Grays of radiation (for reference, about 5 Grays can kill a human). It is so tough that it has been nicknamed "Conan The Bacterium". A subversion of this trope in some regards, since Conan the Bacterium didn't have to "mutate" to survive so much radiation; its radiation immunity comes from its ability to repair damage to its DNA very quickly, and it didn't develop this skill from radiation stress, but from dehydration; it was just lucky that both radiation and dehydration could be survived with the same strategy. If it ever does mutate into something that's not harmless to other life forms, consider the Oh, Crap! potential.
- Chernobyl's songbirds, to some extent. Basically, they're responding to higher amounts of radiation by producing more antioxydants, which help repair damaged DNA. This also has the side effect of prolonging their lives.