Sir Robert Richmond Rex KBE CMG (25 January 1909 – 12 December 1992), was the first Premier of the Pacific island state of Niue.
Rex was born to parents Leslie Lucas Richmond Rex, a European trader on Niue, and Fisimonomono Tufaina of Avatele Village in the south of Niue. He later settled down in Alofi, the capital of Niue, with his wife of that village, Tuagatagaloa, Lady Rex, QSM (1918–2004).
He was the great uncle of the rugby player Frank Bunce.
Rex was Premier of Niue from its establishment as a self-governing territory on 19 October 1974 until his death in 1992. Upon his death in office, he was succeeded by Mititaiagimene Young Vivian, until General Elections the following year resulted in the election of Frank Fakaotimanava Lui into office. Having served 18 years in office, he is Niue's longest serving Premier and probably the Pacific's longest serving head of a government.
Although he was opposed to party politics on Niue, Rex was supported by the Niue People's Action Party after its formation in 1987. During his almost two decades in office, Rex held virtually all Government ministerial portfolios from time to time. His Cabinet of Ministers included prominent Niuean figures such as Dr Enetama Lipitoa, Mititaiagimene Young Vivian and Frank Fakaotimanava Lui, the latter two also going on to become Premiers of Niue.