Common plot elements
A superhero is most often the protagonist of superhero fiction, although some titles, such as Marvels by Kurt Busiek and Alex Ross, use superheroes as secondary characters. A superhero (sometimes rendered super-hero or super hero) is a type of stock character possessing "extraordinary or superhuman powers" and dedicated to protecting the public. Since the debut of the prototypical superhero Superman in 1938, stories of superheroes—ranging from brief episodic adventures to continuing years-long sagas—have dominated American comic books and crossed over into other media. The word itself dates to at least 1917. A female superhero is sometimes called a superheroine (also rendered super-heroine or super heroine). "SUPER HEROES" is a trademark co-owned by DC Comics and Marvel Comics.
By most definitions, characters do not strictly require actual superhuman powers to be deemed superheroes, although terms such as costumed crime fighters or masked vigilantes are sometimes used to refer to those such as Batman and Green Arrow without such powers who share other common superhero traits. Such characters were generally referred to as "mystery men" in the so-called Golden Age of Comic Books to distinguish them from characters with super-powers. Normally, superheroes use their powers to counter day-to-day crime while also combating threats against humanity by their criminal counterparts, supervillains. Long-running superheroes such as Superman, Batman, Spider-Man and Iron Man have a "rogues gallery" of such enemies. One of these supervillains might be the superhero's archenemy. Superheroes will sometimes combat other threats such as aliens, magical/fantasy entities, natural disasters, political ideologies such as Nazism or communism (and their proponents), and godlike or demonic creatures.
A supervillain or supervillainess is a variant of the villain character type, commonly found in comic books, action movies and science fiction in various media. They are sometimes used as foils to superheroes and other heroes. Whereas superheroes often wield fantastic powers, the supervillain possesses commensurate powers and abilities so that he can present a daunting challenge to the hero. Even without actual physical, mystical, superhuman or superalien powers, the supervillain often possesses a genius intellect that allows him to draft complex schemes or create fantastic devices.
Another common trait is possession of considerable resources to help further his aims. Many supervillains share some typical characteristics of real world dictators, mobsters, and terrorists and often have aspirations of world domination or universal leadership. Superheroes and supervillains often mirror each other in their powers, abilities, or origins. In some cases, the only difference between the two is that the hero uses his extraordinary powers to help others, while the villain uses his powers for selfish, destructive or ruthless purposes.
Both superheroes and supervillains often use alter egos while in action. While sometimes the character's real name is publicly known, alter egos are most often used to hide the character's secret identity from their enemies and the public.
With superheroes, the duality of their identities is kept a secret and closely guarded to protect those close to them from being harmed and to prevent them from being called upon constantly, even for problems not serious enough to require their attention.
With supervillains, by contrast, the duality of their identities is kept a secret and closely guarded to conceal their crimes from the general public, so that they may inflict greater harm on the general public, and to enable them to act freely, and hence illegally, without risk of arrest by law-enforcement authorities.
Death in superhero fiction is rarely permanent, as characters who die are often brought back to life through supernatural means or via retcons (retroactive changes to the continuity), the alteration of previously established facts in the continuity of a fictional work. Fans have termed the practice of bringing back dead characters "comic book death".
Another common trait of superhero fiction is the killing off of a superhero's significant other by a supervillain to advance the plot. Comic book writer Gail Simone has coined the term "Women in Refrigerators" (named after an incident in Green Lantern #54 where Kyle Rayner's girlfriend Alex DeWitt is murdered by the supervillain Major Force and stuffed into Rayner's refrigerator) to refer to this practice.
Many works of superhero fiction occur in a shared fictional universe, sometimes (as in the cases of the DC and Marvel Universes) establishing a fictional continuity of thousands of works spread over many decades.
Changes to continuity are also common, ranging from small changes to established continuity, commonly called retcons, to full reboots, erasing all previous continuity.
It is also common for stories works of superhero fiction to contain established characters and setting while occurring outside of the main canon for those characters.
Crossovers often occur between characters of different works of superhero fiction. In comic books, highly publicized "events" are published featuring crossovers between many characters.
Intercompany crossovers, between characters of different continuity, are also common.
Over the history of the comic book genre, writers for major characters' series were required to produce material to strict regular publishing schedules. As such, superhero stories have used a wide variety of story genres such as Fantasy, Science fiction, Mystery, Horror, Crime fiction etc. that put superhero characters in a vast variety and combinations of story settings and fiction tropes with their presence the major common element. As such, it has become an expected element to superhero fiction to be in nearly any story situation, including relatively down-to-Earth drama with their personal lives out of costume.