Serbian Empire

Flag of the Serbian Empire (1346-1371)

Greco-Serbian Empire

Flag of the Greco-Serbian Empire

Civil Flag of Serbia & State Flag of the Principality of Serbia

Flag of the Principality of Serbia (1815-1882). It also serves as the civil flag of both the Kingdom of Serbia (1882-1918) and the Republic of Serbia (adopted in 2004).

Original Flag:
https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Civil_Flag_of_Serbia.svg/640px-Civil_Flag_of_Serbia.svg.png

Republic of Serbia (2004-2010)

Flag of the Republic of Serbia from 2004 to 2010.

Original Flag:
https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Flag_of_Serbia_%282004-2010%29.svg/640px-Flag_of_Serbia_%282004-2010%29.svg.png

Kingdom of Yugoslavia and State Union of Serbia-Montenegro

Flag of Yugoslavia, adopted in 1918. It was the state flag for the Kingdom of Serbs, Croats and Slovenes/Kingdom of Yugoslavia (1918-1943) under a 2:3 proportion, as well as for the Federal Republic of Yugoslavia/State Union of Serbia and Montenegro (1992-2006) under a 1:2 proportion.

In Kaiserreich canon, the flag is also used as the flag for the Federation of Serbs, Croats and Slovenes.

Second Counter Made by MrNazar

Original Flags:
Yugoslavia:
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Flag_of_the_Kingdom_of_Yugoslavia.svg/640px-Flag_of_the_Kingdom_of_Yugoslavia.svg.png

Serbia-Montenegro:
https://upload.wikimedia.org/wikipedia/commons/thumb/9/90/Flag_of_Serbia_and_Montenegro.svg/640px-Flag_of_Serbia_and_Montenegro.svg.png