Key comics are comic books that are historically important to comic book industry fans and collectibles experts. The first appearances of Superman, Batman, or Spider-Man are key comics. The first time that major Marvel characters like Iron Man, Thor, and the Hulk combine to form the Avengers is a key comic.
Pivotal storyline, character deaths, first work of famous creators, and so on, can make a comic a key comic. Another major factor that makes a key comic valuable is the first appearances of major female comic book characters.
