Mahitala Dhibesra Adulyadej Vikrom, the Prince Father, formerly Mahidol Adulyadej, Prince of Songkla or Mahidol Songkla, was the father of King Ananda Mahidol and King Bhumibol Adulyadej of Thailand, and the paternal grandfather of King Vajiralongkorn. He was also regarded as the father of modern medicine and public health in Thailand. He also founded the House of Mahidol or the present Royal Family of Thailand.
Prince Mahidol was the 69th child of King Chulalongkorn and the 7th of Queen Savang Vadhana. His mother also adopted four other royal princes whose commoner mother had died; among them was Prince Rangsit Prayulsak, later Prince of Chainat, who became a very close friend of Prince Mahidol during his childhood. Later in their lives, Prince Rangsit would play a pivotal role in Mahidol's career, and would later be appointed regent to one of Mahidol's sons, Bhumibol.