| Post: | Ambassador |
| Body: | the United States to Nauru |
| Insignia: | US Department of State official seal.svg |
| Insigniasize: | 120 |
| Insigniacaption: | Seal of the United States Department of State |
| Incumbent: | Marie C. Damour |
| Incumbentsince: | February 7, 2023 |
| Nominator: | The President of the United States |
| Appointer: | The President |
| Appointer Qualified: | with Senate advice and consent |
| Inaugural: | Marshall Green as Ambassador Extraordinary and Plenipotentiary |
| Formation: | February 28, 1974 |
| Website: | U.S. Embassy - Suva |
The United States ambassador to Nauru is the official representative of the government of the United States to the government of Nauru. The ambassador is concurrently the ambassador to Fiji, Kiribati, Tonga, and Tuvalu, while residing in Suva, Fiji.
| Marshall Green – Career FSO | Ambassador Extraordinary and Plenipotentiary | February 28, 1974 | October 26, 1974 | July 31, 1975 | ||
| James Ward Hargrove – Political appointee | February 4, 1976 | April 20, 1976 | March 9, 1977 | |||
| Philip Henry Alston – Political appointee | May 17, 1979 | August 13, 1979 | January 23, 1981 | |||
| Robert Dean Nesen – Political appointee | June 17, 1981 | November 20, 1981 | May 2, 1985 | |||
| Laurence W. Lane Jr. – Political appointee | December 6, 1985 | October 17, 1987 | April 29, 1989 | |||
| Melvin Floyd Sembler – Political appointee | October 10, 1989 | June 14, 1990 | February 28, 1993 | |||
| Don Lee Gevirtz – Political appointee | December 19, 1995 | April 24, 1996 | September 28, 1997 | |||
| M. Osman Siddique – Political appointee | August 9, 1999 | October 19, 1999 | June 30, 2001 | |||
| David L. Lyon – Career FSO | November 15, 2002 | August 11, 2004 | July 23, 2005 | |||
| Larry Miles Dinger – Career FSO | June 27, 2005 | August 31, 2005 | July 5, 2008 | |||
| C. Steven McGann – Career FSO | October 6, 2008 | November 24, 2008 | July 13, 2011 | |||
| Frankie A. Reed – Career FSO | August 4, 2011 | July 16, 2012 | January 18, 2015 | |||
| Judith Beth Cefkin – Career FSO | December 11, 2014 | August 12, 2015 | February 25, 2018 | |||
| Michael B. Goldman – Career FSO | Chargé d'Affaires ad interim | February 25, 2018 | N/A | December 23, 2019 | ||
| Joseph Cella | Ambassador Extraordinary and Plenipotentiary | Confirmed: September 17, 2019 | December 23, 2019[1] | January 20, 2021 | ||
| Tony Greubel[2] | Chargé d'Affaires ad interim | January 20, 2021 | N/A | November 23, 2022 | ||
| Marie C. Damour | Ambassador Extraordinary and Plenipotentiary | August 4, 2022 | February 7, 2023 | Incumbent |