Marcus Aurelius Claudius Quintillus (died 270) was a short-lived Roman emperor. An Illyrian, he was likely born in Pannonia Inferior, as is indicated by his coinage. Originating from a low-born family, Quintillus came to prominence with the accession of his brother Claudius Gothicus to the imperial throne in 268. Quintillus was possibly made Procurator of Sardinia during his brother's reign. 

Quintillus was declared emperor either by the Senate or by his brother's soldiers upon the latter's death in 270. Eutropius reports Quintillus to have been elected by soldiers of the Roman army immediately following the death of his brother;  the choice was reportedly approved by the Roman Senate. Historian Joannes Zonaras reports him elected by the Senate itself. Records, however, agree that the legions which had followed Claudius in campaigning along the Danube were either unaware or disapproving of Quintillus' elevation. They instead elevated their current leader Aurelian as emperor.

The few records of Quintillus' reign are contradictory. They disagree on the length of his reign, variously reported to have lasted 17 days (Jerome, Eutropius and Zonaras) or 77 days (Filocalus, Zosimus gives "a few months"). Modern scholars believe "17" to be a misreading of a larger number, as there is an abundance of coins produced during his reign.  Records also disagree on the cause of his death. The Historia Augusta reports him murdered by his own soldiers in reaction to his strict military discipline.  Jerome only reports that he was slain at Aquileia.  Joannes Zonaras reported Quintillus to have committed suicide by opening his veins and bleeding himself to death; John of Antioch reports the suicide to have been assisted by a physician.  Claudius Salmasius noted that Dexippus recorded the death without stating causes. All records, however, agree in placing the death at Aquileia. Quintillus was reportedly survived by his two sons.

Quintillus' claim to be emperor was challenged by Aurelian, who was proclaimed emperor by the legions he commanded. Quintillus' reign only lasted a few weeks. Different sources report his cause of death as murder by his own soldiers, in battle with Aurelian, or by suicide.