Forests are regions of dense trees and other vegetation. Fictional forests vary tremendously depending on the world genre and tone. While some forests in fiction are idyllic, offering solace and inspiration, others are dark and menacing, fraught with danger and uncertainty. While fantasy forests may contain giant trees from which treetop cities hang, paranormal worlds may feature eerie woods where ghosts or cryptids dwell. Forests are home to bandits, elves, lost campers, and bigfoot.

The design of a fictional forest often begins with the design of the terrain upon which it grows. While forests may be located on flat ground, just as often they cover already interesting landscapes. These overgrown regions can then provide unique sublocations within the forest itself. Worldbuilders should consider terrain elements like mountains, hills, canyons, caves, lakes, and rivers. What had been a simple hill now becomes a bluff rising above the tree canopy or what had been a simple river now becomes a meandering waterway beneath the leaves.

Forests, being composed of individual trees and plants, can vary greatly in tone and aesthetic based on what their dominant vegetation is. Old growth forests of deep greens, with moss and vines that grow from giant trees are a very different kind of forest than ones of slender white aspen with yellow, red, and orange leaves. Designers should consider the type of forest they wish to create beginning with the type of trees most commonly found. This may also be an opportunity for worldbuilders to insert fictional plants.

The tone of a forest can be further enhanced by use of weather elements such as fogs and mists, gentle rains, or gentle snows. In addition, forests can undergo extreme change depending on the season.