The planet Venus has been used as a setting in fiction since before the 19th century. Its opaque cloud cover gave science fiction writers free rein to speculate on conditions at its surface—a "cosmic Rorschach test", in the words of science fiction author Stephen L. Gillett. The planet was often depicted as warmer than Earth but still habitable by humans. Depictions of Venus as a lush, verdant paradise, an oceanic planet, or fetid swampland, often inhabited by dinosaur-like beasts or other monsters, became common in early pulp science fiction, particularly between the 1930s and 1950s. Some other stories portrayed it as a desert, or invented more exotic settings. The absence of a common vision resulted in Venus not developing a coherent fictional mythology, in contrast to the image of Mars in fiction.

During the late 19th and early 20th centuries, it was erroneously believed that there were "canals" on the planet Mars. These were a network of long straight lines in the equatorial regions from 60° north to 60° south latitude on Mars, observed by astronomers using early telescopes without photography.