Benbadhanabongse, Prince of Phichai (Thai: เพ็ญพัฒนพงศ์; RTGS: Phenphatthanaphong; 13 September 1882 – 11 November 1909) was a Prince of Siam, a member of the Siamese (later Thailand) royal family. He originated the House of Benbadhana (ราชสกุลเพ็ญพัฒน์). He was a son of Chulalongkorn, King Rama V of Siam.