Quintillus (212-270) was born at Sirmium to a low-born family; only coming to any prominence when his brother Claudius II Gothicus became emperor in 268. When Claudius II died two years later in 270; Quintillus was declared his successor; either by the Roman Senate or by his brother's soldiers.

The exact dates and length of Quintillus' reign are contradictory; lasting anything from 17 to 177 days. Similarly; the cause of his death is unknown; with some sources stating that he was murdered by his own soldiers for his strict military discipline; while others report him being killed in battle against rival claimant Aurelian. Still some sources claim that he committed suicide.

What few records remain of him claim Quintillus to be a moderate and capable ruler; a champion of the Senate and spiritual successor to previous Emperors Galba and Pertinax.