4th-century Roman emperors

Roman emperor from 306 to 337 and first to convert to Christianity (272–337)

Diocletian ( ; ; ; 242/245 – 311/312), nicknamed Jovius, was Roman emperor from 284 until his abdication in 305. He was born Diocles to a family of low status in the Roman province of Dalmatia. As with other Illyrian soldiers of the period, Diocles rose through the ranks of the military early in his career, serving under Aurelian and Probus, and eventually becoming a cavalry commander for the army of Emperor Carus. After the deaths of Carus and his son Numerian on a campaign in Persia, Diocles was proclaimed emperor by the troops, taking the name "Diocletianus". The title was also claimed by C

Roman emperor from 379 to 395

last Pagan Roman emperor, reigned 361 to 363

Honorius (; 9 September 384 – 15 August 423) was Roman emperor from 393 to 423. He was the younger son of emperor Theodosius I and his first wife Aelia Flaccilla. After the death of Theodosius in 395, Honorius, under the regency of Stilicho, ruled the western half of the empire while his brother Arcadius ruled the eastern half. His reign over the Western Roman Empire was precarious and chaotic. In 410, Rome was sacked for the first time since the Battle of the Allia almost 800 years prior.

Roman emperor (317-361)

Roman emperor (250-306)

Roman emperor from 364 to 375

Arcadius ( ; 377 – 1 May 408) was Roman emperor from 383 to his death in 408. He was the eldest son of the Augustus Theodosius I () and his first wife Aelia Flaccilla, and the brother of Honorius (). Arcadius ruled the eastern half of the empire from 395, when their father died, while Honorius ruled the west. In his time, he was seen as a weak ruler dominated by a series of powerful ministers and by his wife, Aelia Eudoxia.

Valens (; ; 328 – 9 August 378) was Roman emperor from 364 to 378. Following a largely unremarkable military career, he was named co-emperor by his elder brother Valentinian I, who gave him the eastern half of the Roman Empire to rule. In 378, Valens was defeated and killed at the Battle of Adrianople against the invading Goths, which astonished contemporaries and marked the beginning of barbarian encroachment into Roman territory.

Valerius Licinianus Licinius (; Greek: Λικίνιος; c. 265 – 325) was Roman emperor from 308 to 324. For most of his reign, he was the colleague and rival of Constantine I, with whom he co-authored the Edict of Milan that granted official toleration to Christians in the Roman Empire. He was finally defeated at the Battle of Chrysopolis (AD 324), and was later executed on the orders of Constantine.

Roman emperor (316-340)

Maximian (; ), nicknamed Herculius, was Roman emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent most of his time on campaign. In late 285, he suppressed rebels in Gaul known as the Bagaudae. From 285 to 288, he fought against Germanic tribes along the Rhine frontier. Together with Diocletian, he launched a scorched earth campaign deep into Alamannic territory in 288, refo

Galerius Valerius Maximianus (; Greek: Γαλέριος; 258 – May 311) was Roman emperor from 305 to 311. He participated in the system of government later known as the Tetrarchy, first acting as caesar under Emperor Diocletian. In this period Galerius obtained victory warring against the Persian Sasanian Empire, defeating Narseh at the battle of Satala in 298 and possibly sacking the Sasanian capital of Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300. Galerius was promoted to augustus upon the abdication of Diocletian in 305, but had to contend

Roman emperor from 363 to 364

Marcus Aurelius Valerius Maxentius ( 283 – 28 October 312) was a Roman emperor from 306 until his death in 312. Despite ruling in Italy and North Africa, and having the recognition of the Senate in Rome, he was not recognized as a legitimate emperor by his fellow emperors.

Gratian (; ; 18 April 359 – 25 August 383) was emperor of the Western Roman Empire from 367 to 383. The eldest son of Valentinian I, Gratian was raised to the rank of Augustus as a child and inherited the West after his father's death in 375. He nominally shared the government with his infant half-brother Valentinian II, who was also acclaimed emperor in Pannonia on Valentinian's death. The East was ruled by his uncle Valens, who was later succeeded by Theodosius I.

early 4th century Roman emperor

Flavius Julius Constans ( 323 – 350), also called Constans I, was Roman emperor from 337 to 350. He held the imperial rank of caesar from 333, and was the youngest son of Constantine the Great.

Roman emperor from 310 to 313

Roman emperor from 375 to 392

late 4th-century Roman emperor of Britain and usurper of the West

early 4th-century Roman emperor

Vetranio (died ) was briefly an imperial usurper and emperor in the Roman Empire in 350, during which time he controlled Illyricum between the rival emperors Magnus Magnentius and Constantius II, eventually capitulating to the latter.

Roman emperor from 316 to 317

emperor of the Western Roman Empire