| Jaan Poska | |
| Office1: | Minister of Foreign Affairs |
| Term Start1: | 24 February 1918 |
| Term End1: | 20 September 1919 |
| Predecessor1: | Position established |
| Successor1: | Ants Piip |
| Office2: | Mayor of Tallinn |
| Term Start2: | 1913 |
| Term End2: | 1917 |
| Predecessor2: | Voldemar Lender |
| Successor2: | Gavriil Beljagin |
| Birth Date: | 24 January 1866 |
| Birth Place: | Laiusevälja, Kreis Dorpat, Governorate of Livonia |
| Death Place: | Tallinn, Estonia |
| Alma Mater: | University of Tartu |
Jaan Poska VR III/1 (in Estonian pronounced as /ˈjɑːn ˈposkɑ/;, Laiusevälja, Kreis Dorpat, Governorate of Livonia – 7 March 1920, Tallinn, Estonia) was an Estonian barrister and politician.
Poska was born the fifth of 12 children of a Russian Orthodox parish schoolmaster and received his secondary education at the Orthodox church's school in Riga. He entered medical school at the University of Tartu, but soon transferred to law where he graduated in 1890. Poska was the first ethnic Estonian admitted to the bar in Tallinn, where he worked as barrister.
Jaan Poska was mayor of Tallinn during 1913–1917. In that position he supported reforms, like reforming healthcare and founding two schools. In April 1917, he became governor of the Autonomous Governorate of Estonia. 1917 the Maapäev refused to recognize the new Bolshevik rule and proclaimed itself the supreme legal authority of Estonia. The Republic of Estonia formally declared independence on 24 February 1918, only to be occupied by the German Empire until the end of World War I. Estonian war of independence against Baltic German and Russian forces lasted from 1918 to 1920.
On 24 February 1918, Poska was appointed the Minister of Foreign Affairs of Estonia. He worked in Western Europe for gaining diplomatic recognition to Estonia and participated in Paris Peace Conference. He led the peace talks with Soviet Russia and achieved Treaty of Tartu which was signed on 2 February 1920, and helped draft the first Estonian constitution.
When Poska died suddenly on 7 March 1920 at the early age of 54, 20,000 Estonians attended his funeral.
Jaan Poska's daughter Vera Poska-Grünthal was a leading Estonian feminist and lawyer who was married to politician and lawyer Timotheus Grünthal. American lawyer Sharon L. Gleason is Jaan Poska's great granddaughter.[1]