An epistolary novel is a novel written as a series of letters. The term is often extended to cover novels that intersperse documents of other kinds with the letters, most commonly diary entries and newspaper clippings, and sometimes considered to include novels composed of documents even if they do not include letters at all. More recently, epistolaries may include electronic documents such as recordings and radio, blog posts, and e-mails. The word epistolary is derived from Latin from the Greek word ἐπιστολή, epistolē, meaning a letter ((see epistle). In German, this type of novel is known as a Briefroman.

The epistolary form can add greater realism to a story, because it mimics the workings of real life. It is thus able to demonstrate differing points of view without recourse to the device of an omniscient narrator. An important strategic device in the epistolary novel for creating the impression of authenticity of the letters is the fictional editor.