Following is an extract of all the Fretwells listed in the 1810 Federal Census for Albemarle County, Virginia.
The William Fretwell listed here is a "phantom," so far as our records go. This William Fretwell is in Albemarle County concurrent with the sons of William Fretwell and Mary Evatt, but he is not one of their sons, so far as our records show.
Note that "our" William (1) has been dead since 1788, so he is not listed.
His son, William (2) died in 1806, so he is not listed. (His second wife, Jemima, is however.)
William Crenshaw Fretwell (3) died in 1807, so he is not listed.
The William listed here could not be William (4), the son of James Fretwell, who would be far too young to be listed as a householder.
The same goes for William (5), the son of Thomas Fretwell, and William (6), the son of John Thomas Fretwell Sr.
Of course, the names of all "our" William's descendants are not known, so this "phantom" William could be a descendant of William and Mary, but it seems strange that we would have no record of some male of this age in "our" William's will.
He could be a Fretwell from a different family line, arrived in Albemarle county sometime between the 1785 census and the 1810 census. He is 45 years of age or older at the time of this census, as is his wife. They have no children living at home with them.
As an interesting side note, there are 36 white Fretwells, and they own 58 slaves.