Rangsit Prayurasakdi, Prince of Chai Nat (Thai: สมเด็จพระเจ้าบรมวงศ์เธอ พระองค์เจ้ารังสิตประยูรศักดิ์ กรมพระยาชัยนาทนเรนทร; RTGS: Somdet Phra Chao Borommawong Thoe Pra Ong Chao Rangsitprayurasak Krom Phraya Chainatnarenthon; 12 November 1885 – 7 April 1951) was the Thai Founder of the Public Health Ministry and as Regent of Thailand.

After the early death of his mother, Prince Rangsit and his elder sister Princess Yaovabha Bongsanid were adopted by Queen Savang Vadhana.

Today, a statue of Prince Rangsit stands in front of Thailand's Ministry of Public Health, of which he is the founding father.

Since the new king at first planned to finish his education abroad, Prince Rangsit was appointed Regent of Thailand on June 16, 1946, as well as chairman of the Supreme Council of State since 1947.

In March 1951, Prince Rangsit died of a heart attack while in bed at Vidyu Palace on Wireless Road in Bangkok.