Rameshwar Singh Thakur GCIE KCB KBE (16 January 1860 – 3 July 1929) was the maharaja of Darbhanga in the Mithila region from 1898 to his death.

He became maharaja on the death of his elder brother Lakshmeshwar Singh, who died without issue.

He was appointed to the Indian Civil Service in 1878, serving as assistant magistrate successively at Darbhanga, Chhapra, and Bhagalpur.

He was exempted from attendance at the Civil Courts and was appointed a Member of the Bengal Legislative Council in 1885.

[1] He was a member of the Council of India of the governor general of India in 1899 and on 21 September 1904 was appointed a non-officiating member representing the Bengal Provinces, along with Gopal Krishna Gokhale from Bombay Province.