Regents
The Regent of Thailand (ผู้สำเร็จราชการแทนพระองค์) as stated in the Constitution of Thailand is appointed either by the monarch himself or by the Privy Council of Thailand, the appointment must be countersigned by the President of the National Assembly of Thailand. The circumstances for appointment of a regent in the constitution is unclear it states that a regent can be appointed : "Whenever the king is absent from the kingdom or unable to perform His functions for any reason whatsoever" (Chapter 2, Section 18). So far a regent has only been appointed when the monarch has been in minority, when the monarch takes a foreign trip and when the monarch enters the Sangha as a monk. A regent can be either a commoner or a member of the royal family depending on the circumstances.
Read more about this topic: Chakri Dynasty