USS Spadefish (SSN-668), a Sturgeon-class submarine, was the second ship of the United States Navy to be named for the spadefish, a spiny-finned fish found in coastal waters of the western Atlantic from Cuba to Cape Cod.

The Sturgeon class was a class of nuclear-powered fast attack submarines (SSN) in service with the United States Navy from the 1960s until 2004. They were the "workhorses" of the Navy's attack submarine fleet throughout much of the Cold War. The boats were phased out in the 1990s and early 21st century, as their successors, the Los Angeles, followed by the Seawolf and Virginia-class boats, entered service.