The first duke of Estonia ( ) was appointed in 1220 by King Valdemar II of Denmark after the Danish conquest of Estonia during the Livonian crusade. The title was resumed by the kings of Denmark since 1269. During the 1266-82 reign of the queen dowager Margaret Sambiria, the title lady of Estonia was used. In 1332, after Christopher II died, his second son Otto inherited the title of the duke of Estonia. Valdemar III assumed the title in 1338. The dukes of Estonia rarely resided in Estonia. To govern the Duchy of Estonia, the king of Denmark and royal counsellors appointed the Lieutenant, who resided in Reval. The king of Denmark sold the duchy to the Teutonic Order in 1346, but Christian I reassumed the title of duke of Estonia in 1456. After the Livonian War, Estonia became part of the Swedish Empire, and the title was gained by kings of Sweden. Crown Prince Gustav Adolph was already Duke of Estonia 1607-1611 before he became King, but then officially abolished all Swedish duchies in 1618. The title was resumed by the Russian tsars after the Great Northern War and Treaty of Nystad when Estonia became part of the Russian Empire. The last duke of Estonia was Nicholas II of Russia.

Danish dukes of Estonia

The Duchy of Estonia (1219–1346) was part of the Kingdom of Denmark, where the House of Estridsen reigned. In 1346, Northern Estonia is sold to the Livonian Order. This Order was already ruling Southern Estonia since 1237.

Swedish dukes of Estonia

The Duchy of Estonia (1561–1721) or Swedish Estonia was part of the Swedish Empire.

House of Vasa

1561– 29 September 1568||||Tre Kronor (castle), 13 December 1533 son of Gustav I and Catherine of Saxe-Lauenburg||Karin Månsdotter||Died (Poisoned) while imprisoned in Örbyhus Castle, 26 February 1577. Aged 43, buried at Västerås Cathedral Gunilla Bielke (1585–1597)||Tre Kronor (castle), 17 November 1592, aged 54, buried at Uppsala Cathedral Constance of Austria (1605–1631)||Warsaw, Poland, 30 April 1632, aged 65, buried at Wawel Cathedral, Kraków, Poland 22 March 1604 – 30 October 1611 also as regent Duke Charles, 1599–1604||||Tre Kronor (castle), 4 October 1550 son of Gustav I and Margaret Leijonhufvud||Maria of Palatinate-Simmern (1579–1589), Christina of Holstein-Gottorp (1592–1611)||Nyköping Castle, 30 October 1611, aged 61, buried at Strängnäs Cathedral

House of Palatinate-Zweibrücken, a branch of the House of Wittelsbach

13 February 1660 – 5 April 1697||||Tre Kronor (castle), 24 November 1655 son of Charles X and Hedwig Eleonora of Holstein-Gottorp||Ulrike Eleonora of Denmark||Tre Kronor (castle), 5 April 1697, aged 41, buried in Riddarholmen Church

House of Hesse

Ulrika Eleonora of Sweden||Stockholm, 25 March 1751, aged 74, buried in Riddarholmen Church On 10 September 1721, Sweden ceded Estonia to the Tsardom of Russia, in the Treaty of Nystad.

Governors during Swedish rule