A legendary creature is a fictional creature. Some such as the dragon, the griffin or the unicorn have their origin in traditional myth and have at one time been believed to be real creatures. Others were based on real creatures, originating in garbled accounts of travellers' tales; such as the "Vegetable Lamb of Tartary", which supposedly grew tethered to the earth (and was actually the cotton bush). Even the traditional unicorn may have come from garbled stories about the rhinoceros. Examples of the semi-mythical creatures can be found in medieval bestiaries.
Conversely, some creatures once believed to be mythological have been found in recent times, such as the giant squid. As such, the boundaries between what is recognised in human culture as being a mythological and existent creature have been subject to the limitations of human perception.
Often, legendary creatures are chimeras, a combination of two or more real animals. For example, a pegasus is a combination of a horse and bird, a centaur of a man and horse, a minotaur of a man and bull.
Many legendary creatures appear prominently in fantasy fiction, often adding additional depth to the concept of the creature. These creatures are often claimed to have supernatural powers or knowledge, or guard some object of great value, which becomes critical to the plot of the story in which it is found. (See fantasy bestiary for a list of these as well as newer creations.)
Jorge Luis Borges wrote and edited the Book of Imaginary Beings in 1969, expanding his original 1957 Spanish edition El Libro de los Seres Imaginarios. This book contains descriptions of 120 mythical beasts from folklore and literature.
In modern times, consciously fictional creatures invented to test ideas are sometimes given mock scientific names; in a certain sense these are the new legendary creatures. One famous example is Homo economicus, the imaginary person who behaves fully rationally in the sense required by economic theory. Modern fantasy games and literature, from Tolkien down, also make extensive use of existing legendary creatures and have also invented new ones, some of which have passed into common usage and are thus becoming modern legends.