The name Vasilios is a Greek masculine given name derived from the Greek word "basileus," meaning "king" or "monarch." It has its origins in ancient Greece and has been in use for over two millennia.

Vasilios was a common name among the ruling classes in the Byzantine Empire, where it was associated with royalty and nobility. The name gained popularity during the reign of the Byzantine Emperor Basil I, who ruled from 867 to 886 AD and founded the Macedonian dynasty.

In Greek mythology, Vasilios is associated with the legendary figure of Basilius, a warrior and hero who fought alongside the gods. This association with bravery and valor contributed to the name's significance and appeal.

One of the earliest recorded instances of the name Vasilios dates back to the 4th century AD, when Saint Basil the Great, a prominent theologian and Bishop of Caesarea, was born in 330 AD. His work had a profound influence on the development of Christian theology and monastic traditions.

Throughout history, several notable figures have borne the name Vasilios. One such figure was Vasilios Digenis Akritas, a legendary Byzantine hero and warrior who lived in the 10th century AD and was celebrated in epic poems for his bravery in defending the Byzantine Empire's eastern borders.

Another prominent figure was Vasilios Argyropoulos (c. 1457-1534), a Greek Renaissance scholar and humanist who played a significant role in the revival of Greek learning in Italy during the 15th and 16th centuries.

In the 19th century, Vasilios Konstantinou (1835-1899) was a Greek military officer and revolutionary who fought for the liberation of Crete from Ottoman rule, becoming a national hero in Greece.

More recently, Vasilios Tsitsanis (1915-1984) was a renowned Greek composer and singer, widely considered one of the most influential figures in the development of the Greek rebetiko music genre.

The name Vasilios has also been associated with royalty and nobility in other cultures. For example, Vasili III (1479-1533) was a Grand Prince of Moscow and the first ruler of a unified Russia.