Casperius Aelianus served as Praetorian Prefect under the emperors Domitian and Nerva.
Aelianus succeeded in his demands, greatly weakening the authority of the Emperor so much that Nerva realized that his position was no longer tenable without the support of an heir who had the approval of the Roman army.
Within two or three months Nerva announced the adoption of the highly respected general Trajan as his successor.
Trajan, who was in Cologne, accepted the empire, and stayed north of the Alps for some time.
Cassius Dio writes: "He sent for Aelianus and the praetorians who had mutinied against Nerva, pretending that he was going to employ them for some purpose, and then put them out of the way.