Phra Bat Somdet Phra Nangklao Chao Yu Hua or Rama III (31 March 1787 – 2 April 1851) is the third monarch of Siam under the House of Chakri, ruling from 21 July 1824 to 2 April 1851.

He succeeds his father, Phutthaloetla Naphalai, as the King of Siam.

His succession is unusual according to the traditions because Nangklao is the son of a concubine rather than a of a queen.

He surpasses Prince Mongkut, who is a legitimate son of Phutthaloetla Naphalai, born to Queen Srisuriyendra.

During Nangklao's reign, the military hegemony of Siam is observed through a series of intensive wars in Laos, Cambodia, and Vietnam.

Nangklao is known for his affection for Chinese culture.

As a young prince, he is also known as a great businessman who conducts profitable trades with China and enriches the royal treasury.