Valentinian Dynasty
The Valentinian dynasty, yet another lower-class military family (this time of Pannonian extraction), is in a very loose sense a marital continuation of the Constantinian dynasty (Gratianus was son-in-law of Constantius II, the penultimate Constantinian Emperor). Although the dynastic founder, Valentinian I, had made his career as a soldier and general, he was not a "Barracks Emperor"; rather, he was elevated to the purple by a conclave of senior generals and civil officials after the death of Jovian.
Read more about this topic: Roman Emperor (Dominate)