Vassilios or Vassileios, also transliterated Vasileios, Vasilios, Vassilis or Vasilis (Greek: Βασίλειος or Βασίλης), is a Greek given name, the origin of Basil.
In ancient/medieval/Byzantine context, it is also transliterated as Basileios.
It is directly descended from the word "King", Greek: Βασιλιάς.
It descends from the Greek language.