Phetracha (alternative spellings: Bedraja, P'etraja, Petraja, Petratcha; also called Phra Phetracha; Thai: เพทราชา; 1632–1703) was a king of the Ayutthaya kingdom in Thailand, usurping the throne from his predecessor King Narai and founding the Ban Phlu Luang dynasty, the final one of the Ayutthaya kingdom.
Originally a member of king Narai's extended family (two of his relatives were among Narai's wives), he was a trusted councilor of Narai, and leader of the Royal Elephant Corps. However, in 1688 he led the Siamese revolution of 1688, had Narai's heirs executed, and by marrying Narai's only daughter took the throne of Ayutthaya kingdom upon Narai's death. He reversed the pro-Western policies of Narai, ejecting foreigners from the kingdom, and launched the Siege of Bangkok, to exile all French troops from Siam. As a result, Siam stayed isolated from Western contact until the 19th century.
Upon his death in February 1703, Phetracha was succeeded by his eldest son Prince Sua, who took the title of Sanphet VIII.