- Born: Cir 1818, Pennsylvania
- Marriage: Hannah circa 1841 in Pennsylvania
- Died: After 1880, Franklin Township, Fayette Co., PA
see notes on William's daughter, Sarah, for 1850 and 1860 census facts.
The 1870 Federal Census for Menallen Township, Fayette Co., PA, Connellsville P.O., page 272A records William (51 - PA) and Hannah (44 - PA) Gillen (sic) with children Clark (21 - PA), Smith (16 - PA), and Franklin (14 - Illinois). William is a House Carpenter.
The 1880 Federal Census for Franklin Township, Fayette Co., PA, District 39, page 182A records William (65 - PA) and Hannah (53 - PA) Gilleland (sic) with Frank (23 - PA) and his wife Elizabeth (21 - PA). William is a Carpenter. Nearby is George (64) and Margaret S. (48) Gilleland with children David P. (24), Mary C. (23), Lewis McC (21), Sarah J. (13), and Ida Bell (12). Nearby in Upper Middleton, Menallen Township, Fayette Co., PA, District 46, page 316B is Clark Gilleland (28) with his wife Malissa (28) and children Clarance (8) and John H. (2). Clark is a Brick Layer.
Note: William's probable father, Adam, is recorded as Adam Gilleland in the 1840 Federal Census for Franklin Township, Fayette Co., PA.
William married Hannah circa 1841 in Pennsylvania. (Hannah was born circa 1825 in Pennsylvania and died after 1880 in Franklin Township, Fayette Co., PA.)