Worldwide Guide to Women in Leadership
Serbia Heads of State
Srbija was under Osman Rule from 1389, gained autonomy 1815, and became Independent 1878 and a Kingdom 1881, after world war an autonomous republic in the Federal Republic of Yugoslavia

Also see  Serbia Ministers and Female Presidents of Unterstate Entities

1254-63 Dowager Duchess Anna of Macva

1280-82 Dowager Duchess Erszebet of Macva

1355-56 Regent Dowager Tsarina Helena of Bulgaria of Serbia
1555-59 Reigning Dowager Lady of "Serbia's Bulgaria lands between the lower Vardar and the Mesta" and the Chalcidic Peninsula
On the death of her husband, Stefan Uroš IV Dušan, she was regent and reigned her dowries until she  became a nun under the religious name Elisaveta in 1359, but continued to play an active role in politics. She was the daughter of Sratsimir of Kran and Petritsa and the sister of Tsar Ivan Alexander of Bulgaria. She (d. 1374).

1372-89 Dowager Despotess Milica Eugenia Vratkovic of Rudnik
1389-97 De-facto Ruler
Regent for son Stefan Lazarevic. She was very wise and tactical in the difficult times during the Turkish invasion.

1397-1412 De-Facto Ruler Mara Brankovic of Kosovo
Together with her sons.

1458 Regent Dowager Queen Jelena Palailologina of Serbia
Together with other regents. Died as nun in 1473

1463-86 Pretender Dowager Queen Katarina of Bosnia-Serbia
The state was under Osman occupation. She inherited the claim after her son, Stjepan Tomasevic, who died 1461. She died 1486 in Rome.

1514-20 Regent Dowager Despina Helena of Serbia
Her first husband was Jovan Brankovic, despot of Sebia in 1493–1502. After his dead she was married to Croatian nobleman Ivanis Berislavic who then became the Serbian despot (1502–14). After the death of Ivanis she conducted the affairs of state in place of her minor son, the despot Stjepan Berislavic (1514 – 35).