Marcus Aemilius Aemilianus (c. 207 - 253), was Roman Emperor for about three months in 253.

Aemilian was born into an obscure family from the Roman province of Africa. He is thought to have married Cornelia Supera but other details of his early life are unknown. In 251, the governor of Moesia Superior, Trebonianus Gallus, was acclaimed emperor following the death of Trajan Decius and his two sons. Aemilianus was sent to replace him, serving as governor for both Moesia and Pannonia. His primary responsibility was to assure peace along the Danube frontier, which had been harassed in the previous years by the Goths led by king Cniva.

Gallus secured the throne and controlled the outbreak of plague that devastated the city of Rome. However, he was not popular with the army, mainly due to the humiliating treaties signed in 251 with the Goths and to the attack of King Shapur I of Persia against Syria. Aemilian personified this discontent and refused to pay the tribute due to Cniva in 253. The Goths then invaded the Roman provinces to demand reparation but Aemilian inspired his troops to defeat them early that summer. The army was satisfied to see the Roman honour restored and acclaimed Aemilian as emperor. In order to make the claim real, he abandoned his provinces and marched into Italy. Gallus and his co-emperor and son Volusianus gathered an army, ordered reinforcements from the Rhine border and prepared to defend the throne from usurpation. Aemilian was not impressed and continued his march, trusting in the value of his veteran legions. A battle was never fought because Gallus' soldiers, anticipating defeat, assassinated him and his son and declared for Aemilian.

The Roman senate readily accepted this new emperor and confirmed the title of Augustus for Aemilian. However, Valerian, the governor of the Rhine provinces, still loyal to the now dead Gallus, was on his way southwards to reinforce, and now avenge, his former Emperor. When the two armies faced each other near Spoletium that September, Aemilian, like Gallus before him, was assassinated by his own troops when they saw Valerian's army would be impossible to beat.Some sources say that Aemilianus had a mental problem in the 3rd cranial nerve and suffered multiple strokes in his life, however the evidence is poor and the only sources are those written centuries after his death.