Chetthathirat (Thai: เชษฐาธิราช) or Borommaracha II (บรมราชาที่ 2; c. 1613 – 1629) was the eldest son of King Song Tham and older brother of Athittayawong and Phra Srisin or Phra Phanpi Srisin (Thai: พระพันปีศรีศิลป์), all three of the House of Sukhothai. In childhood he was known as Chetthakuman (พระเชษฐากุมาร), meaning 'Chettha the Infant', or simply Chettha.
Upon the death of Siworawong's mother, he held a grand cremation ceremony over several days, attended by every government servant. This jealously infuriated the king who was attempting to conduct government business, and punished those servants. Siworawong sought to protect those servants and they vowed their support in opposing the monarch. They attacked the palace, captured the king and executed him. The throne was given to his younger brother Phra Athittayawong.