| Erhard Arnold Julius Dehio | |
| Image Upright: | 0.90 |
| Office1: | Lord mayor of Tallinn |
| Term Start1: | March 1918 |
| Term End1: | 13 November 1918 |
| Predecessor1: | Voldemar Vöölmann (as chair of the city government of Tallinn) |
| Successor1: | Aleksander Pallas (as acting deputy mayor) |
| Birth Date: | 16 January 1855 |
| Birth Place: | Reval, Russian Empire (modern-day Tallinn, Estonia) |
| Death Place: | Bad Oeynhausen, Germany |
Erhard Arnold Julius Dehio (16 January 1855 – 12 July 1940)[1] was a Baltic German merchant and politician who was the lord mayor of Tallinn from March 1918 to 13 November 1918, with Alexander Riesenkampff as second mayor. A notable grain exporter, he traded throughout Europe in the late 19th century. First a city councilor, he was the lord mayor of Tallinn during the German occupation of Estonia during World War I, when the German Empire occupied most of newly independent Estonia, including Tallinn. After the occupation ended and Estonia became an independent republic, Dehio resigned as mayor and left for Germany, eventually setting up his headquarters in Lübeck. He was succeeded by Aleksander Pallas. He would be the last Baltic German mayor of Tallinn. He died in 1940 in Bad Oeynhausen.