When William Henry Mullins was born on 25 May 1866, in Hempstead, Arkansas, United States, his father, William Maston Mullins, was 20 and his mother, Nancy Louella Louisa Briggs, was 30. He married Sarah Perthenia Adkisson on 7 January 1889, in Freestone, Texas, United States. They were the parents of at least 6 sons and 2 daughters. He lived in Rock Creek Township, Stephens, Oklahoma, United States in 1920 and Hulen Township, Comanche, Oklahoma, United States in 1930. He died on 14 June 1934, in Lawton, Comanche, Oklahoma, United States, at the age of 68, and was buried in Stephens, Oklahoma, United States.