William was the son of Thomas and Martha (James) Elliott of Estill County, Kentucky, and the brother of Amelia, Phillip J., Elizabeth., Martha J., Dawson D., Daniel S., Nancy, Thomas, and Sarah. His father was a farmer in Estill County, and William followed in his father's footsteps. William married Ann Eliza "Annie" Harris in 1871. Their children were Martha, Nora, John, Robert, Fannie, and Lizzie. William died in 1917 and is buried in Red Hill Cemetery in Panola, Kentucky.
Sources
"United States Census, 1850," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M659-QPB : 9 November 2014), William D Elliott in household of Thomas Elliott, Estill county, Estill, Kentucky, United States.
"United States Census, 1870," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MX7B-PJK : 17 October 2014), William D Elliott in household of Thomas Elliott, Kentucky, United States.
"United States Census, 1880," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MCCX-82W : 11 August 2016), William D Elliott, Crooked Creek, Estill, Kentucky, United States.
"United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M94M-GX2 : accessed 31 March 2017), William Elliott, Magisterial District 5, Red Lick, Estill, Kentucky, United States.
"United States Census, 1910," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M28R-F9K : accessed 31 March 2017), William D Elliott, Red Lick, Estill, Kentucky, United States.