Louis Fred Pfeifer (June 19, 1876 – c. 1917) was a private in the United States Marine Corps who received the Medal of Honor for risking his life to rescue several shipmates during a fire aboard USS Petrel (PG-2). After receiving the Medal of Honor he continued to serve in the Marine Corps and upon reenlistment changed his name back to Pfeifer until he was discharged in 1917.