How about NIGHT.
My GG Grandparents James and Martha Night, with children, were listed as farming in the 1850 and 1860 census for Linden, Perry Co., Tennessee. The spelling was "NIGHT". Neither of them could read or write and this may have been the census enumerator, "taking liberties". (This is my father's, mother' line.)
Sometime around 1864/65 GG Grandpa James apparently drowned. In the 1870 census GG Grandma Martha A. "KNIGHT" showed up in Decaturville, Decatur Co., Tennessee, with their children. My G Grandfather William James KNIGHT was one of these children. Decatur County is directly across the Tennessee River from Perry County. The name has remained KNIGHT since then.
I have seen entries in some of the other forums that NIGHT ancestors, seemed to have almost automatically had the spelling changed to KNIGHT during or after the Civil War. I have run into the same thing with my own last name, official recorders will spell the name as they think it should be spelled!
Come to think of it, the spelling of my wife's maiden name also changed, while her GG Grandfather served in the Civil War.