The Defiant class vessel is Starfleet's first warship and one of its most advanced ship designs, conceived in response to the Borg threat. Starfleet's Advanced Starship Design Bureau at the Utopia Planitia Fleet Yards began the project in 2366. Admiral Batelle Toh was responsible for the project. Benjamin Sisko was also part of the project. After the Borg threat was deemed lower, research and production for these vessels slowed. Engineering problems – particularly in regard to the small ship's overpowered engines – led Starfleet to mothball the project. However, Starfleet puts the class into production during the Dominion War.

The design is a semi-saucer fore and a squared-off aft. A short, rectangular extension housing the navigational deflector and an emergency matter/antimatter warhead attaches at the bow. The warp engines are housed on either side of the ship. Unusual for Starfleet vessels, the Defiant class' warp engines are not parallel; their axis intersects less than a ship-length aft of the starship. Another trait distinguishing this class is that it was specifically designed for war. Ablative hull armor allows Defiant class ships to take a considerable beating even after the incapacitation of its shields. The ship has few of the creature comforts that are found on most Starfleet vessels and has small racked bunk-style quarters. The infirmary is small and the design does not include science labs. The normal crew complement is forty six personnel.