Queen Somanass Waddhanawathy or Somanass Queen Waddhanawathy (Thai: โสมนัสวัฒนาวดี; RTGS: Somanat Watthanawadi; 1834–1852), was the first queen of Mongkut, though for only nine months.
Princess Somanass was a daughter of Prince Lakkhananukhun (son of Nangklao) and Ngiu Suvarnadat. Since her father was Phra Ong Chao, Somanass was destined to be Mom Chao. However, Nangklao specially granted her the title of Phra Ong Chao i.e. princess.
In 1851, upon his coronation, Mongkut married Princess Somanass, them she became the queen. In the same year she gave birth to a prince: Somdet Chaofa Somanass, but the prince shortly died. Queen Somanass herself died two months after.