Arbogast

Arbogast or Arbogastes (died 8 September 394) was a Roman army officer of Frankish origin. He won distinction in the service of the emperor Gratian, and was subsequently entrusted by Theodosius I with the guardianship of the underage Valentinian II. After the death of Valentinian under suspicious circumstances, and the subsequent elevation of Eugenius to Augustus of the Western Roman Empire by Arbogast, a civil war ensued in which both Eugenius and Arbogast perished.

Source: Wikipedia — https://en.wikipedia.org/wiki/Arbogast_(magister_militum)