Tiberius was the second Roman Emperor, reigning from 14 AD to 37 AD following the death of his stepfather, Augustus. He was one of Rome's greatest generals, whose conquests in Pannonia, Dalmatia, and Raetia laid the foundations for the northern frontier. Despite his military successes, his reign was marked by a withdrawn and suspicious nature, leading to a reputation as a dark and reclusive ruler. In his final years, he retired to the island of Capri, leaving Rome's administration largely in the hands of the ambitious praetorian prefect, Sejanus.