Archon is an old Greek term for a higher Councillor or Judge I believe too!
JB
In "Byzantine" Greek it was a more or less generic term for ruler or leader.
"The Unknown Archon" is a term used to described the legendary founder of Serbia.
The Unknown Archon (Serbian: непознати архонт / nepoznati arhont), Unknown Knez (непознати кнез / nepoznati knez),[1] Unnamed Serb Archon (неименовани српски архонт / neimenovani srpski arhont),[2] or simply Serb Archon (српски архонт / srpski arhont),[3] refers to the Serbian prince who led the White Serbs from their homeland to settle in the Balkans during the reign of Byzantine Emperor Heraclius (610–641), as mentioned in Emperor Constantine VII's De Administrando Imperio (950s). The work states that he was the progenitor of the first Serbian dynasty (known as the Vlastimirović), and that he died before the settlement of the Bulgars (680).[4] Serbian historiography commonly treats him as the first Serbian ruler.
https://en.wikipedia.org/wiki/Unknown_Archon
It's too bad nobody thought to put in a mention of "unknown archons" or "The Unknown Archon". in "Return of the Archons".