In the original film, Godzilla is portrayed as a terrible and destructive monster born from nuclear materials. Following the first movie's success, Toho quickly followed up with the sequel Godzilla Raids Again. In this film, Godzilla battles the monster Anguirus beginning the trend where Godzilla would fight other giant creatures. In the fifth film, Ghidorah, the Three-Headed Monster, Godzilla takes the role of a hero – a role he plays until the end of the Showa series. As the protagonist, Godzilla is frequently charged with protecting Japan against other monsters, aliens, and other evil characters.
The Showa-era movies played on the fears and interests of audiences during the period in which they were made. For instance, Godzilla was designed to warn people about the negative side effects of nuclear weapons. Likewise, Godzilla vs. Hedorah carried a message about the dangers of pollution. As space exploration and the Space Age were popular in the late 1960s and early 1970s, many of Godzilla's films featured fights with alien monsters or an alien invasion. For instance, in the movie Destroy All Monsters, an alien race takes control of Earth's monsters only to later lose control and be destroyed by their captives.