Sri Raj Rajeshwar Maharajadhiraja Narendra Maharaja Shiromani Sri Dungar Singh Bahadur (22 August 1854 – 19 August 1887) was a Maharaja of the princely state of Bikaner from 1872 to 1887. The eldest of three sons of Maharaj Sri Lal Singh (16 December 1831 – 17 September 1887) a relative of a distant branch of the Rathore clan, Dungar Singh was an enlightened and progressive monarch. He aided the British during the Second Afghan War (of Sherlock Holmes fame) in 1878 by supplying 800 camels. Deeply involved in education, he opened the first Bikaner public schools and college during his reign, also organising the first modern police force, an up-to-date budget and fiscal standards, dispensaries, a post office, and a civil surgeon, reforming the jails as well.
Dungar Singh died in 1887, only a few days shy of his 33rd birthday, his father following him in death a month later. He was succeeded by his youngest brother, Ganga Singh, whom he had adopted for himself as his son.