Mercurius (Hungarian: Merkúr)[1] was a Hungarian distinguished nobleman and perhaps the first known voivode of Transylvania, who held the office during the reign of Coloman, King of Hungary.
[1] Two royal charters issued in 1111 and 1113 mention Mercurius as "princeps Ultrasilvanus", but he may have been only an important landowner in Transylvania without holding any specific office.
[2] The title voivode was first documented[where?]
specifically in 1199.
also mentions a "Mercurio comes Bellegratae", which means "count (ispán) of Fehér", and this record may point to the same person.