William was the 10th of 12 children of Armstead Barnes (1809-1854) and Elizabeth Dowell Barnes (1814-1896). Armstead Barnes is buried in Meadville Cemetery, Meade County, Kentucky. Elizabeth Dowell Barnes is buried in Redmon Cemetery, Cooke County, Texas.

William Barnes was married to Elizabeth "Lizzie" Ellen Miller on June 3, 1875 at Henry Martin's house in Larue County, Kentucky.

William bought his sibling's shares of the old Armstead and Elizabeth Dowell Barnes family farm and built a wood frame, 2-story house with wood siding on the property. It has long since been known in the area as "the old Billy Barnes house." In 2001, Junior Dowell said this house was once the finest in the area. The house still stands today, and has been used for storage. Though the condition of the old house has declined, the front part of the house still appears to be sturdy. With permission, Bud Roberts and I went in the house and up the staircase into the 2nd floor. (Larry E. Barnes, 2001). Thomas J. Stith owns and lives on this property today (2006).

Thomas J. Stith said that he recalls Mr. Barnes (William) playing the fiddle while Thomas Stith's mother Lena Stith accompanied him the piano.

William and Lizzie Barnes had children;
1. (Rev.) Ernest Walker Barnes (1876-1958), married Minnie Lou Crady.
2. Annie C. Barnes (1878-1961), married Ernest L. Dowell.
3. Leora Ellen Barnes (1880-1960), married Chester Taylor Sipes.
4. Armistead Edward Barnes (1883-1956), married Annie Evelyn Taber. They had children; a daughter who died in 1908; Daisy Eleanor Barnes, born July 18, 1910, died 1992 in Tennessee (SSDI). Eleanor married Cliff Templin, one of their last addresses was Tullahoma, Tennessee. One child was Joan T. (Templin) Haeberle.
5. Lettie Lee Barnes (1885-1969), married James Taber, brother of Annie Evelyn Taber.
6. Robert Hicks Barnes (1888-1968), married Susie B. Shacklett. Burial in Buck Grove Baptist Church Cemetery, Meade County, Kentucky.