Louis Thomas Gunnis Leonowens (25 October 1856 – 17 February 1919) was a British subject who was the basis of a fictional character in the 1944 novel Anna and the King of Siam. He is a tritagonist of the 1999's animated film The King and I, and voiced by Adam Wylie.
Leonowens was the son of Anna Leonowens nee Edwards, an Anglo-Indian who had never visited Britain, and Thomas Leon Owens, an Irish-born, India-raised clerk, who married in India in 1849. The couple left India for Singapore in 1852.
Louis was born at Lynton, Western Australia, where his father was working for the Commissariat. In 1857, the family moved to Indonesia, where his father was a hotel manager. His father died in 1859, and his mother moved to Singapore with Louis and his elder sister, telling the British expatriate community there that she was a genteel Welsh woman, the widow of a British army officer who had unfortunately lost her fortune.
His mother's story was believed, and she was invited, in 1862, to teach the wives and children of King Mongkut of Siam (now Thailand). After sending Louis's sister to England to get a British education, his mother took him to Bangkok. He was raised in the Siamese royal palace for nearly six years and was schooled by his mother alongside the royal children, until 1867. He was sent to Europe to complete his education. By 1874, Louis was in the U.S. with his mother, but he had accumulated debts. He fled the U.S. and was estranged from his mother for 19 years.