Felix Xerxes Gygax was born March 30, 1884, in Hancock Township, Osborne County, Kansas. He was raised on the farm of his parents, Rudolf and Regina (Zimmerman) Gygax, and attended the local rural one-room schools. After graduation from Downs High School Felix taught school for a couple of years until he won an appointment to the United States Naval Academy at Annapolis, Maryland, in 1903. He graduated on September 12, 1906, and was assigned to the U.S.S. Kearsage in time to participate in the 14-month around-the-world voyage of the Great White Fleet ordered by President Theodore Roosevelt from December 1907 to September 1909. Upon his return he was transferred to the U.S.S. Minnesota.
On November 16, 1911, Lieutenant Gygax married Estelle Ise at the Ise family home in Lawrence, Kansas. The couple later raised two sons, Felix Jr., and Rex Gygax. A week after the wedding Felix reported for duty as a naval inspector at Winterthur, Switzerland, where submarine diesel engines were being built in a diesel factory for the U.S. Navy. When he learned that the Swiss wanted to charge him income tax, he succeeded in being appointed naval attaché at Bern, Switzerland, which exempted him from the tax.
Felix was then appointed first officer in charge of the submarine school in New London, Connecticut, until 1920, when he assisted in the establishment of the submarine base at Pearl Harbor in Hawaii. He then served in the Naval Department in Washington, D.C., and now held the rank of admiral.
In 1933 Admiral Gygax was made Professor of Naval Science and Tactics at the University of California at Berkeley, after which he commanded the U.S.S. Augusta, then the flagship of the Asiatic Fleet. After a brief command of Cruiser Division 3 he was transferred to command of the Norfolk (VA) Naval Yard in 1940, also receiving a presidential designation as Rear Admiral. In 1942 he was appointed commandant of the First Naval District in Boston, Massachusetts, where he was in charge of the Boston Naval Yard and later the Norfolk Navy Yard.
When Rear Admiral Gygax retired August 1, 1946, he was the holder of the Legion of Merit and was an honorary commander of the Most Excellent Order of the British Empire. With his wife he built an adobe house in Rancho Santa Fe, California, and settled into a quiet retirement. He passed away February 24, 1977, in San Diego, California, and was buried with full military honors in Arlington National Cemetery at Washington, D.C.