What is the greek name for William or bill?

The Greek equivalent of the name William is "VasiliOS" (Βασίλειος). This name is derived from the Greek Word "basileus," meaning "king." While there isn't a direct translation for "Bill," it is often considered a diminutive of William. In informal contexts, "Bill" might be adapted as "Vasilis" (Βασίλης) in Greek.