Phaya Lithai, also known as Phra Maha Thammaracha I, or Loe Thai, is a king of the Sukhothai kingdom, reigning from roughly 1347 until his death in 1368.

Lithai is the son of Lerthai, also known as Loethai or Lelithai.

The exact chronology of Lithai's rise to the throne is unclear.

Popular tradition names him as the fourth king of Sukhothai, but dynastic records seem to indicate that at least one other king (Nguanamthom) ruled between Lithai and his father, as well as the regent Phaya Sai Songkhram who ruled during Lerthai's absence following the death of Ram Khamhaeng the Great.