Wassil is of Slavic origin, specifically from Bulgaria and other Eastern European countries. It is derived from the Slavic element 'vasile', which means 'king' or 'ruler'. Wassil has been traditionally used as a given name in these regions for centuries.
"The name Wassil saw a slight rise and fall between 1916 to 1919, with peak years at six births each for 1916 and 1919."