Tshudpud Namgyal (1785–1863) was king of Sikkim from 1793–1863. He gained independence from Nepal in 1815 and ruled under a British protectorate from 1861.
Under his father Tenzing Namgyal, most of Sikkim was appropriated by Nepal. Tshudpud Namgyal returned to Sikkim in 1793 to reclaim the throne. Because the capital of Rabdentse was too close to the Nepalese border, he shifted the capital to Tumlong.
Sikkim allied itself with the British in India, who also considered Nepal an enemy. Nepal overran most of the region, sparking the Gurkha War in 1814 with the British East India Company. The Sugauli Treaty and Treaty of Titalia returned the annexed territory to Sikkim in 1817.
In 1835, Tshudpud Namgyal ceded Darjeeling to the HEIC for an annual fee, but this relation was broken off sharply after he seized two British scientists in Sikkim, Joseph Dalton Hooker and Archibald Campbell. This led to two British military attacks in 1850 and 1861, resulting in the annexation of Sikkim by 1861. The same year, Tshudpud was granted the title of Maharaja of Sikkim by the British, and he abdicated the following year. At his death in 1863, aged 78, he had ruled Sikkim for 69 years, making him the longest-reigning Chogyal in history; as well, he was also the oldest ever Chogyal of Sikkim.