Billee is of American origin, derived from the Old French 'Guillaume', meaning 'resolute protection'. It is a variant spelling of William and shares its popularity among unisex names in recent years.
The name Billee experienced periods of popularity and decline over the years, with a significant peak in 1926 (21 births) and another notable high in 1956 (22 births). However, it seems to have become quite uncommon recently, with fewer than 10 births per year since 1979.