Crown Prince of Thailand
สยามมกุฎราชกุมาร
Standard of the Crown Prince
Incumbent Vacant since 13 October 2016
Style	His Royal Highness
Status	Heir apparent
Member of	Chakri dynasty
Appointer	Monarch
Term length	Life tenure or until accession as Sovereign
Inaugural holder	Vajirunhis
Formation	14 January 1886; 138 years ago (1886-01-14)

The Crown Prince of Thailand (or Siam; Thai: สยามมกุฎราชกุมาร; RTGS: Sayammakutratchakuman; lit. the royal son of Siam) is a title held by the heir apparent to the Thai throne. First created by King Chulalongkorn (Rama V) in 1886, for his son Prince Maha Vajirunhis, the king's eldest son by a royal wife Queen Savang Vadhana. Prior to this, the Siamese throne did not have a law or formal system regulating the royal succession. In 1688 King Petracha of Ayutthaya created the title of Front Palace, which by the Rattanakosin period had become the main title granted to the heir presumptive to the throne. However few Front Palaces have succeeded to the throne this way, with the exception of King Buddha Loetla Nabhalai (Rama II) in 1809. After the death of Bovorn Wichaichan in 1885, the title of Front Palace was abolished and replaced with the title of Crown Prince, who became heir apparent to the throne.

In 1924 King Vajiravudh (Rama VI) promulgated the 1924 Palace Law of Succession to regulate the succession, this law essentially barred females, children of commoner wives or children of foreign wives to the throne, it also re-affirmed agnatic primogeniture, or succession through the male-line by seniority. This law also affected the individuals who could become Crown Prince. Since its creation three Princes have been raised to this title, and two have succeeded to the throne.

The title in Thai, Sayammakutratchakuman, comes from conjugation of the words Sayam (Siam), Sanskrit makut (meaning “crown”), ratcha from Sanskrit rāj, and kuman from Sanskrit kumār (meaning “son”).

Crown Princes

Crown Princes of Thailand
Picture	Name	Relationship to monarch	Mother	Birth	Receive title	Ceased to be Crown Prince
	Maha Vajirunhis	Eldest son with queens of King Rama V	Queen Savang Vadhana	27 June 1878	14 January 1886[1]	4 January 1895 (death)
	Maha Vajiravudh (later King Rama VI)	Third son with queens of King Rama V	Queen Saovabha Phongsri	1 January 1881	4 January 1895[2]	23 October 1910 (ascension)
	Maha Vajiralongkorn (later King Rama X)	Only son of King Rama IX	Queen Sirikit	28 July 1952	28 December 1972[3]	13 October 2016 (ascension)[4]

Heirs-apparent and heirs-presumptive to the throne

List of heirs apparent and heirs presumptive since 1886, those in bold succeeded to the throne as King.

Heirs to the Thai Throne
Heir	Status	Relationship to monarch	Became Heir		Ceased to be Heir		Next in line of succession (Relation to heir)	Monarch
			Date	Reason	Date	Reason
Crown Prince Maha Vajirunhis	Heir apparent	Eldest son with queens[a]	14 January 1886	New creation	4 January 1895	Died of typhoid	Prince Vajiravudh, Prince of Ayutthaya 1886–1895, younger half-brother	Rama V
Crown Prince Maha Vajiravudh	Heir apparent	Third son with queens[b]	4 January 1895	Elder half-brother died	23 October 1910	Father died; became king	Prince Chakrabongse Bhuvanath, Prince of Phitsanulok 1895–1910, younger brother
Prince Chakrabongse Bhuvanath, Prince of Phitsanulok	Heir presumptive	Younger brother	23 October 1910	Elder brother became king	13 June 1920	Died of pneumonia	Prince Asdang Dejavudh, Prince of Nakhon Ratchasima 1910–1920, younger brother	Rama VI
Prince Asdang Dejavudh, Prince of Nakhon Ratchasima	Heir presumptive	Younger brother	13 June 1920	Elder brother died	9 February 1924	Died of nephrosis	Prince Chudadhuj Dharadilok, Prince of Phetchabun 1910–1923, younger brother
							Prince Varananda Dhavaj Chudadhuj 1923–1924, nephew
Prince Varananda Dhavaj Chudadhuj	Heir presumptive	Nephew	9 February 1924	Uncle died	2 September 1924	Skipped by the royal command[c][5]	Prince Prajadhipok Sakdidej, Prince of Sukhothai 1924, uncle
Prince Prajadhipok Sakdidej, Prince of Sukhothai	Heir presumptive	Younger brother	2 September 1924	Nephew was skipped	25 November 1925	Elder brother died; became king	Prince Mahidol Adulyadej, Prince of Songkla 1924–1925, elder half-brother
Prince Mahidol Adulyadej, Prince of Songkla	Heir presumptive	Elder half-brother	25 November 1925	Younger half-brother became King	24 September 1929	Died of pneumonia	Prince Ananda Mahidol 1925–1929, eldest son	Rama VII
Prince Ananda Mahidol	Heir presumptive	Half-nephew	24 September 1929	Father died	2 March 1935	Abdication of half-uncle; became king	Prince Bhumibol Adulyadej 1929–1935, younger brother
Prince Bhumibol Adulyadej	Heir presumptive	Younger brother	2 March 1935	Elder brother became King	9 June 1946	Elder brother died; became King	Prince Paribatra Sukhumbandhu, Prince of Nakhon Sawan 1935–1944, half-uncle	Rama VIII
							Prince Chumbhotbongs Paribatra 1944–1946, half-first cousin
Prince Chumbhotbongs Paribatra, Prince of Nakhon Sawan II	Heir presumptive	Half-first cousin	9 June 1946	Half-first cousin became king	28 July 1952	Son born to king	Prince Sukhumabhinanda 1946–1952, half-brother	Rama IX
Crown Prince Maha Vajiralongkorn	Heir apparent	Only Son	28 July 1952	Born	13 October 2016	Father died; became King	Prince Chumbhotbongs Paribatra, Prince of Nakhon Sawan II 1952–1959, half-first cousin once removed
							Prince Sukhumabhinanda 1959–1974, half-first cousin once removed
							Princess Maha Chakri Sirindhorn, Princess Royal 1974–1978, younger sister
							Princess Bajrakitiyabha 1978–1979, only daughter
							Prince Juthavachara Mahidol 1979–1997, eldest son
							Princess Bajrakitiyabha 1997–2005, eldest daughter[d]
							Prince Dipangkorn Rasmijoti 2005–2016, only recognised son
Prince Dipangkorn Rasmijoti	Heir presumptive	Only recognised son[e]	13 October 2016	Father became king	Incumbent		Princess Bajrakitiyabha, Princess Rajasarini Siribajra 2016–present, elder half-sister	Rama X