Somdej Toh (1788-1872), known formally as Phra Buddhacharn Toh Phomarangsi, was one of the most famous Buddhist monks during Thailand's Rattanakosin Period. Somdej Toh was born in Kamphaeng Phet Province, possibly the son of King Rama I. He studied the Buddhist scriptures of the Pāli Canon with several Buddhist masters. After becoming a well-known monk, he became the preceptor for Prince Mongkut, later King Rama IV, when Mongkut became a monk. During Rama IV's reign Somdej Toh was given the ceremonial name Phra Buddhacharn Toh Phomarangsi.