Inside the Xanth collection by Piers Anthony, the Naga certainly are a race of human-headed serpents which can change in between completely human and serpent forms, such as any species and sizing of snake. Phaya Nak or Phaya Nāga (Thai: พญานาค; RTGS: phaya nak; lit. 'lord of Nāga', phaya derived https://slot-naga2656666.tinyblogging.com/facts-about-naga26-revealed-74195488