Phra Athittayawong (Thai: พระอาทิตยวงศ์; born 1618) King Athitayawong was the shortest-reigning monarch of Ayutthaya, only for 38 days in 1629 and the last king of the Sukhothai dynasty.
Prince Athitayawong was the son of King Songtham and his principal wife. His elder brother and mother were executed in 1629 in Okya Sri Suriyawong’s coup. The child prince was raised to the throne with Sri Suriyawong (Thai: ออกญาศรีสุริยวงศ์) acting as regent. However, Sri Suriyawong persuaded his supporters and the nobility to give him full power and crowned him as the second king. Then it was decided that there would be no two kings in the same kingdom and Athitayawong was executed at Wat Kok Phraya (Thai: วัดโคกพระยา) soon, ending the Sukhothai dynasty. Sri Suriyawong ascended the throne as King Prasat Thong.