Athittayawong[1] (Thai: อาทิตยวงศ์, Ādityavaṅśa; born 1618) was the shortest-reigning monarch of Ayutthaya, only for 36 days in 1629 and the last king of the Sukhothai dynasty.

[2]: 55 Prince Athitayawong was the son of King Songtham and his principal wife.

Athittayawong was dethroned and Siworawong assumed the title Somdet Phrachao Prasat Thong.

[3]: 215–216 Athitayawong was executed at Wat Kok Phraya (Thai: วัดโคกพระยา) soon after being deposed, ending the Sukhothai dynasty.

Siworawong ascended the throne as the first king of the Prasat Thong dynasty.