Sebastianus (died before 445 or in 450) was a general of the Western Roman Empire, son-in-law of Bonifacius. A good soldier and advisor, and an orthodox Catholic, Sebastianus was son-in-law of the powerful Bonifacius, comes Africae in 420s, nominated magister militum praesentalis and patrician by the Empress Galla Placidia in 432. The elevation of Bonifacius disturbed another influential general of the empire, the magister militum praesentalis Flavius Aetius, who had fought and won several campaigns in Gaul; fearing that the promotion of Bonifacius to such an elevated rank (Aetius was not a patrician) would have brought his own dismissal, Aetius took the initiative and attacked Bonifacius, who won the Battle of Ravenna (432) but died for the wounds received.