House of Sundarakul na Jolburi

Sundarakul na Jolburi (Thai: สุนทรกุล ณ ชลบุรี) is a Thai family which traces its ancestry to Prince Sundarabhubej or Krom Khun (prince of the second class) Sundarabhubej (กรมขุนสุนทรภูเบศร์) of Siam.

Prince Sundarabhubej was a Chonburi-commoner by birth, later elevated to princely status by King Phutthayotfa Chulalok (Rama I)'s royal command. He did not have royal blood, but became sworn brothers with the Front Palace Prince Maha Sura Singhanat, the king's younger brother, hence the royal grant of the Thai nobiliary particle "na". The family name was one of many formally granted by King Vajiravudh, (Rama VI, r. 1910–1925.)