Hollywood has been drawing on superhero stories and comic books for inspiration since the earliest serials in the Golden Age. Since then, everything from one-off movies to expansive franchises have dominated cinema with their interesting depictions of superheroes. With the genre generating billions of dollars for Hollywood, there's no sign of superhero films stopping any time soon. Now, it has become common for every major superhero to expect at least a trilogy.
Source：https://www.cbr.com/superhero-sequels-surpassed-original/
