Gabriel Bethlen was Prince of Transylvania from 1613 to 1629 and Duke of Opole from 1622 to 1625. He was also King-elect of Hungary from 1620 to 1621, but he never took control of the whole kingdom. Bethlen, supported by the Ottomans, led his Calvinist principality against the Habsburgs and their Catholic allies.

The Prince of Transylvania was the head of state of the Principality of Transylvania from the last decades of the 16th century until the middle of the 18th century. John Sigismund Zápolya was the first to adopt the title in 1570, but its use only became stable from 1576.