He had three children with his wife, Beatrice: son, William C. de Mille; son, Cecil B. DeMille; and daughter, Agnes Beatrice (born 1891; died 1895), who died of spinal meningitis.
He died of typhoid fever at 4 p.m. of February 9, 1893, at his home in Pompton, NJ. His illness lasted about ten days.
He was the son of Margaret Mutter Blount (Hoyt) and William Edward deMille. He had English, German, Scottish, and Dutch ancestry.