Roman emperor Aurelian ruled from 270 to 275. His military triumphs reunited the Roman Empire and put an end to the Crisis of the Third Century. He built the Aurelian Walls in Rome. Known as the Restitutor Orbis, he defeated the barbarian armies of the Goths and the Alamanni.
Boris III became Tsar of the Kingdom of Bulgaria in the wake of Bulgaria's defeat in First World War. He is noted for legitimating the 1923 Bulgarian coup d'état and joining Axis Powers during Second World War. He however refrained from participating in German invasion of Soviet Union and resisted attempts of the Germans in deporting Bulgarian Jews during Holocaust.
Roman emperor (in the East) Galerius was a staunch pagan and opposed Christianity. He persuaded his predecessor Emperor Diocletian to issue an edict to initiate persecution of the Christians. After Galerius became Roman emperor (in the East), he continued persecution and eventually issued Edict of Toleration, officially ending Diocletianic Persecution of Christianity in the eastern part of the Roman Empire.
Krum was the ruler of Bulgaria from 803 until his demise in 814. An able administrator, Krum helped expand the Bulgarian territory, which doubled in size during his reign. Krum is also remembered for introducing the first known written law code in the history of Bulgaria, which established him as a strict but just ruler.
Alexander Joseph or Alexander of Battenberg was a prince of Bulgaria from 29 April 1879 to 7 September 1886. He was forced to abdicate in 1886 by pro-Russian Bulgarian Army officers during a coup d'état. After abdicating, Alexander went on to serve in the Austrian Army as a general.