Sudhammarāja, a monarch of the 10th century, is recorded in the Ayutthaya Testimonies as the ruler of Phitsanulok and Phra Nakhon Sawan Buri. He is described as having ascended the throne at the age of 15, succeeding his father, Sai Nam Peung, and ruling the polity for a period of 35 years. Based on retrospective chronology, his reign is estimated to have extended from 922 to 957 CE, suggesting his birth year was approximately 907 CE. Sudhammarāja entered into matrimony with Śrīprajārājadevī (ศิริประชาราชเทวี); however, no extant record provides information concerning their progeny.