Gaius Septimius Severus Aper (c. 175 - 211/212) was a Roman aristocrat. He was appointed Consul Ordinarius in 207 with the otherwise unknown Lucius Annius Maximus.
Aper came from Leptis Magna and was probably a grandson of the Consul Suffectus of July 153, Publius Septimius Aper. Aper is possibly the same person called Afer in the Historia Augusta, who at the end of the year 211 or 212 was executed on command of the emperor Caracalla.