The last Chogyal of Sikkim was Palden Thondup Namgyal. He was born on 23 August 1923 and died on 29 December 1982. He was the 13th Chogyal of Sikkim, a hereditary Buddhist monarchy in the Himalayas. He was educated in India and the United Kingdom, and served as the head of state of Sikkim from 1947 to 1975. In 1975, Sikkim was merged with India, and Palden Thondup Namgyal was deposed. He lived in exile in the United States until his death in 1982.
Palden Thondup Namgyal was born in Gangtok, Sikkim, the son of Tashi Namgyal, the 12th Chogyal of Sikkim, and Hope Cooke, an American socialite. He was educated at the Lawrence School in Sanawar, India, and at the University of Cambridge in the United Kingdom. After his education, he returned to Sikkim and served as his father’s assistant. In 1947, his father died, and Palden Thondup Namgyal became the 13th Chogyal of Sikkim.
As Chogyal, Palden Thondup Namgyal was a popular figure. He was known for his progressive policies and his efforts to modernize Sikkim. He also worked to improve relations between Sikkim and India. In 1975, however, Sikkim was merged with India, and Palden Thondup Namgyal was deposed. He lived in exile in the United States until his death in 1982.
The other options are incorrect. Wangchuk Tenzing Namgyal was the 11th Chogyal of Sikkim. Tashi Namgyal was the 12th Chogyal of Sikkim. Sidkeong Namgyal was the 10th Chogyal of Sikkim.