Donald Elmer Koster was the only child of Alice (Getty) and Elmer Koster. He was born on June 18, 1927 in Dundee, Michigan.

According to the 1950 census, he lived at the Puget Sound Naval Shipyard in Kitsap, Washington.

On February 6, 1960, he married Donna Clarke in San Diego, California.

On February 1, 2011, Donald died in La Mesa, San Diego County, California at the age of 83.