The ancient Roman flag that was used during the first years of the Byzantine Empire. It is said that it was designed by Field Marshal Gaius Marius and contains a silvery eagle with open wings and golden thunderbolts in its talons. The letters "SPQR" stand for "Senatus PopulusQue Romanus", that is "Roman Senate and People".

The flag of the Byzantine Emperor Constantine the Great [List Of Emperors]. It consists of a combination of the Cross of Saint George and the letters "BBBB" that were the initials of the phrase "Βασιλεύς Βασιλέων Βασιλεύων Βασιλεύσιν" {Vasilefs Vasileon Vasilevon Vasilefsin}, that is "King of Kings Ruling over Kings". At a later time the phrase was replaced by "Βασιλεύ Βασιλέων Βασιλέα Βοήθει" {Vasilef Vasileon Vasilea Voithi}, that is "King of Kings Help the King".

The flag of the Byzantine Empire, after 395 A.D. Until the restoration of the Roman Eagle by Emperor Julian [List Of Emperors], the Cross, introduced for the first time by Emperor Constantine the Great [List Of Emperors], is the dominant sign in the design of the Byzantine Empire's flags.

The flag of the Byzantine Emperor Michael Palaeologus [List Of Emperors]. On August 15th, 1261, Michael Palaeologus recaptured Constantinople from the Venetians who had occupied it in 1204, during the Fourth Crusade. The two crowns symbolize the two capitals of the Empire, that is Constantinople and Nicaea {Nikea ~ Νίκαια}. Nicaea was the capital of the Empire during the time Constantinople was in the hands of the Crusaders. This flag was used until the fall of the Empire.

The flag of the Byzantine Emperor Constantine Palaeologus [List Of Emperors]. A variation of the Byzantine flag, with the Double-headed Eagle appearing in different versions. It has the letters "Τούτω Νίκα" {Touto Nika}, that is "IN HOC SIGNO VINCES", [Definition].