| Friedrich Sthamer | |
| Office: | First Mayor of Hamburg and President of the Hamburg Senate |
| Term Start: | January 1920 |
| Term End: | February 1920 |
| Predecessor: | Werner von Melle |
| Successor: | Arnold Diestel |
| Office2: | German Ambassador to the United Kingdom |
| Term Start2: | 1920 |
| Term End2: | 1930 |
| Predecessor2: | Karl Max von Lichnowsky[1] |
| Successor2: | Konstantin von Neurath |
| Birth Date: | 24 November 1856 |
| Birth Place: | Groß Weeden |
| Death Place: | Ratzeburg |
| Nationality: | German |
| Alma Mater: | Ruperto Carola Lipsiensis Georgia Augusta |
| Occupation: | Lawyer |
Gustav Friedrich Carl Johann Sthamer (24 November 1856 - 29 June 1931) was a German lawyer, First Mayor of Hamburg, and ambassador.
Sthamer was born on 24 November 1856 in Groß Weeden, part of the municipality Rondeshagen. He studied law at the universities of Heidelberg, Leipzig, and Göttingen. In 1879, Sthamer became a lawyer in Hamburg, and in 1892, chairman of Hamburg's bar association. 1901 - 1904, Sthamer was member of the Hamburg Parliament, and elected to the Senate of Hamburg in 1904. During the First World War, Sthamer was president of the civil government of the occupied Antwerp.
In 1919, Sthamer was elected to the Senate of Hamburg and became First Mayor of Hamburg in 1920. After a short term in office, Sthamer resigned because he was appointed as German ambassador to the United Kingdom.
Sthamer died on 29 June 1931.