A ficton is a fictional setting created by writing any fictional story or series of stories.

The term was coined by Robert Heinlein in his novel The Number of the Beast. Here Heinlein gives Oz in The Wizard of Oz and Wonderland in Alice in Wonderland as examples of fictons.

Some fictons look remarkably like our own world, and have the same physical laws and history as ours. In the extreme case of historical novels it may be impossible to prove that the events did not happen exactly as described, so the ficton in which they occur is indistinguishable from the factual universe. In other fictons either history, physics or both are radically different to the factual world, and there is a spectrum in between. A few fictons do not lie neatly on this spectrum, notably the ficton in which the Star Wars series is set, which is described as long ago, in a universe far away...

A series of stories may be based on a single ficton or on many related fictons. The radio plays of The Goons and the television series The Monkees paid little attention to continuity between episodes, so in a sense each is set in its own ficton although there is much material in common. The series Yes Minister, on the other hand, was written as a consistent set of incidents within a single ficton.

A single ficton which is the basis of many individual stories is called a fictional universe.

There are many instances of series originally written for slightly different fictons which have later been incorporated into a fictional universe. For example, Carl Barks' stories of Scrooge McDuck, a character he invented, were only loosely consistent. However later writers have resorted to retcons in order to create a consistent fictional universe across the entire series. As another example, Isaac Asimov's series of novels based on his Foundation trilogy was not originally intended to be consistent with his Robot stories, and he later made minor modifications to the Robot series to integrate most of his fictional writing into a single epic.