This data collection describes international and civil wars for the years 1816-1992.
The Naval History and Heritage Command website provides a table called Casualties: U. S. Navy and Marine Corps, Personnel Killed and Wounded in Wars, Conflicts, Terrorist Acts, and Other Hostile Incidents.
Defense Casualty Analysis System (DCAS) collects U.S. casualty information on warfighters who have fallen in global or regional conflicts involving the United States. This site is maintained by the Defense Manpower Data Center (DMDC).
The National Archives have made state-level lists of casualties from the Korean War and Vietnam War.
Current information from the U.S. Department of Defense.