The USS Defiant was a nuclear submarine of the U.S. Navy.
The Defiant was scuttled by an Atlantean warship for trespassing. Though the crew could be saved by the Justice League, King Arthur of Atlantis denied the Justice League's request to salvage the nuclear material from the sub's reactor. This led to an international incident. Unbeknownst to the King, Orm had the material removed in secret and used it to power the Doomsday Thermal Reactor.
- To date, the U.S. Navy has had no ships named Defiant, only "Defiance" (the name has been given to three ships, none of which are currently in service). The name "Defiant" does belong to several starships in Star Trek.