The USS Relentless (NCC-75637) was a Defiant-class Starfleet vessel in service during the late 24th century. Construction on the Relentless began at Utopia Planitia Fleet Yards in 2373, as part of a wave of Defiant-class vessels ordered by Admiral James Leyton. The ship was not completed until after the Federation Civil War, and was launched in 2375. Lieutenant John Meadows served as security chief and tactical officer on the Relentless, and Ensign Matt Murr was the ship's conn officer.