King Naresuan the Great (1555 - April 25 1605, also sometimes called Naret or the Black Prince) was king of Siam (today Thailand) from 1590 until his death in 1605. During his reign Siam had the biggest territorial extent in history.

Born in Phitsanulok, Naresuan was taken captive by the Burmese to ensure the fidelity of his father Maha Tammaraja, who became king of the Ayutthaya kingdom after it was occupied by the Burmese in 1569. After spending nine years of his youth at Pegu under the courtesy of the Burmese King, Burinnaung the Great, Naresuan was exchanged with his sister Princess Suparntevi when he was 16 years old, and became governor of Phitsanulok. He was highly trained by the Burmese King in martial arts, literature, mitilary strategies and became as one of the Prince in the Burmese Palace.

In 1584 the tributary relation with Burma was cancelled, which was inevitably followed by a vigorous attack by the Burmese army. Naresuan foght back against the attack, and in 1586 he occupied Lannathai, a buffer state between the two kingdoms.

1590 the king died, and Naresuan also officially became the leader of the kingdom. 1591 the Burmese started another attack, which was cancelled when the Burmese crown prince Minchit Sra was killed by Naresuan in Nong Sarai (Suphanburi). The following year Naresuan himself attacked Tenasserim, as well as Cambodia in 1593.

Naresuan died in 1605 during another battle with the Burmese, stabbed by Burmese soldiers in an attempt to cross a garisson's wall in Muang Hang. His brother Ekathotsarotgarrison became his successor.