Sir Robert Rex (b. 1909 - 12 December 1992) was premier of the Pacific island state of Niue from its establishment as a self-governing territory in October 1974 until his death in 1992. Upon his death in office, he was succeeded by Young Vivian.

Although he was opposed to party politics on Niue, he was supported by the Niue People's Action Party after its formation in 1987.