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.

John Sigismund Zápolya or Szapolyai was King of Hungary as John II from 1540 to 1551 and from 1556 to 1570, and the first Prince of Transylvania, from 1570 to his death. He was the only son of John I, King of Hungary, and Isabella of Poland. John I ruled parts of the Kingdom of Hungary with the support of the Ottoman Sultan Suleiman; the remaining areas were ruled by Ferdinand I of Habsburg, who also ruled Austria and Bohemia. The two kings concluded a peace treaty in 1538 acknowledging Ferdinand's right to reunite Hungary after John I's death, though shortly after John Sigismund's birth, and on his deathbed, John I bequeathed his realm to his son. The late king's staunchest supporters elected the infant John Sigismund king, but he was not crowned with the Holy Crown of Hungary.