Phra Bat Somdet Phra Poramintharamaha Chulalongkorn Phra Chunla Chom Klao Chao Yu Hua (Thai: พระบาทสมเด็จพระปรมินทรมหาจุฬาลงกรณ์ฯ พระจุลจอมเกล้าเจ้าอยู่หัว), or Rama V (20 September 1853 – 23 October 1910) was the fifth monarch of Siam under the House of Chakri. He was known to the Siamese of his time as Phra Phuttha Chao Luang (พระพุทธเจ้าหลวง – The Royal Buddha). He is considered one of the greatest kings of Siam. His reign was characterized by the modernization of Siam, immense government and social reforms, and territorial cessions to the British Empire and French Indochina. As Siam was threatened by Western expansionism, Chulalongkorn, through his policies and acts, managed to save Siam from being colonized. All his reforms were dedicated to Siam’s insurance of survival in the midst of Western colonialism, so that Chulalongkorn earned the epithet Phra Piya Maharat (พระปิยมหาราช – The Great Beloved King).

King Chulalongkorn was born on 20 September 1853 to King Mongkut and Queen Debsirindra and given the name Chulalongkorn. In 1861, he was designated Krommameun Pikanesuarn Surasangkat. His father gave him a broad education, including instruction from European tutors such as Anna Leonowens. In 1866, he became a novice monk for six months in Wat Bawonniwet according to royal tradition. Upon his return to his secular life in 1867, he was designated Krommakhun Pinit Prachanat (กรมขุนพินิตประชานาถ.)