Marcus Aemilius Aemilianus (c. 207 – September 253), also known as Aemilian, was Roman emperor for two months in 253.

Commander of the Moesian troops, he obtained an important victory against the invading Goths and was, for this reason, acclaimed emperor by his army. He then moved quickly to Roman Italy, where he defeated Emperor Trebonianus Gallus at the Battle of Interamna Nahars in August 253, only to be killed by his own men a month later when another general, Valerian, proclaimed himself emperor and moved against Aemilian with a larger army.

Aemilian was born in the Roman province of Africa. According to the 4th century source Epitome de Caesaribus, he was a Moor born at Girba (modern Djerba, an island off the coast of Tunisia) and was born around the year 207, as he died at the age of 47 (Romans used inclusive counting). The 12th-century historian Joannes Zonaras, who calls him a Libyan rather than a Moor, and another chronicle of the 13th century hold that he was forty at the time of his death in 253.

Regarding his lineage, there are two versions, both exaggerated: while Eutropius and his translator Paeanius probably defame a failed usurper when they say that he was from an insignificant family, John of Antioch may refer to Aemilian's propaganda when he says that the usurper used his ancestry to take power. His praenomen and nomen, reinforced by his cognomen, suggest a descent from a native African who obtained Roman citizenship during the Second Triumvirate, in which his land was ruled by Marcus Aemilius Lepidus.

Aemilian married Cornelia Supera, a woman of African origin; the year of their marriage is unknown, but since both were from the same place, it is possible they married before Aemilian left Africa.

During the reign of Trebonianus Gallus and his son Volusianus (251–253), Aemilian was sent to the Balkans to command an army. His primary responsibility was to assure peace along the Danube frontier, which had been subject to several attacks by the Goths led by king Cniva.

Gallus secured the throne after the death of Emperor Decius at the hands of Cniva in the Battle of Abrittus (251), and later had to manage an outbreak of plague that devastated Rome. He was not popular with the army, mainly due to humiliating treaties signed in 251 with the Goths and King Shapur I of Persia who attacked Syria. According to John of Antioch, upon his appointment to the Moesian command, Aemilian was already envious of Gallus and plotted treachery against him. He was also an opponent of the Roman Senate, and his seditious plans are confirmed by Jerome and Jordanes.

In 253, the Goths, led by king Cniva, claimed they had not received the tribute due from the Romans according to the treaty of 251. They crossed the border and attacked Cappadocia, Pessinus, and Ephesus. Modern historians believe that this missing payment was not a change in Roman policy, and the Goths were more likely trying to capitalize on their military prowess. Aemilian had command of the army assigned to defend the area, but the recent defeat at the Battle of Abrittus put his troops on edge. Aemilian exhorted them, reminding them of Roman honor (according to Zosimus) and promising tribute from the Goths (according to Zonaras). The Romans took the Goths by surprise, killing most of them, followed by an invasion of Goth territory resulting in booty and the liberation of prisoners. The Roman soldiers, gathered by Aemilian, acclaimed him emperor. Jordanes claims, however, that Aemilian's troops plundered Roman territory, rather than keep the tribute of the Goths.