Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward Cirker and his wife, Blanche. It primarily publishes reissues, books no longer published by their original publishers. These are often, but not always, books in the public domain. The original published editions may be scarce or historically significant. Dover republishes these books, making them available at a significantly reduced cost.

Dover is well known for its reprints of classic works of literature, classical sheet music and of public-domain images from the 18th and 19th centuries. Dover also publishes an extensive collection of mathematical, scientific and engineering texts. It often targets its reprints at a niche market such as wood working.

Most Dover reprints are facsimiles by photo process of the originals, retaining the original pagination and typeset, sometimes with a new introduction. Dover will usually add new and more colorful cover art to its paper-bound editions. They retitle some books to make them more in line with modern usage and categorization. For example, the book Woodward's National Architect was retitled A Victorian Housebuilder's Guide.

The Cirkers started the business selling remaindered textbooks by mail from their apartment in Queens, New York City. The company published its first book, Tables of Functions with Formulas and Curves, when the German copyright was voided by the United States as a result of World War II. The book was an unexpected success and established the Dover business model of publishing esoteric works at a low price. One of Dover's best sellers was Albert Einstein's The Principle of Relativity, which Einstein reluctantly agreed to republish despite his concerns that it was outdated.

Dover was influential in transforming the paperback book market. In 1951 it issued some of the earliest standard-sized paperbacks, a format that became known as a trade paperback. Since the 1960s, the vast majority of Dover's titles have been paper-bound books of various sizes. Dover paperbacks were noted for their quality of manufacture (see below), unlike most paperbacks which were held together with glue and subject to page drop-out.

Beginning in the 1950s Dover also issued a series of Listen & Learn language courses prepared primarily using teachers from Columbia University.

For a time, Dover also published a catalog of LP phonograph records. Some, such as selected recordings of Schubert's solo and chamber works featuring pianist Friedrich Wührer, were reissues of earlier monaural releases from other labels. Noteworthy among Dover's original issues was an extensive series documenting pianist Beveridge Webster in literature ranging from Beethoven's Hammerklavier sonata to the second piano sonata by Roger Sessions. Dover's foray into recordings, however, was not as successful as its core business of book republication, and the company eventually abandoned it.

Starting in the 1990s Dover has published a specialized line of low-cost reprints of public domain literature known as "Dover Thrift Editions", which are generally priced at US$5 or less. They also have several lines of foreign language books.

Hayward Cirker died in 2000 at the age of 82. In that same year, Dover Publications was acquired by Courier Corporation. Courier was acquired by RR Donnelley in 2015.

Early Dover books were noted for their quality. On the back of these paperbacks, Dover wrote:

We have made every effort to make this the best book possible. Our paper is opaque with minimal show-through; it will not discolor or become brittle with age. Pages are sewn in signatures, in the method traditionally used for the best books and will not drop out as so often happens with paper backs held with glue. Books open flat for easy reference. The binding will not crack or split. This is a permanent book.