Overview
Faustina ( 361 – after 366) was an Empress of the Roman Empire and third wife of Emperor Constantius II. The main source for her biography is the account of historian Ammianus Marcellinus. Her origins and other names are unknown.
Marriage
Constantius married her in Antioch in 361, after the death of his second wife, Eusebia in 360. Ammianus simply reports that the marriage took place while Constantius was wintering in Antioch, taking a break from the ongoing Roman–Persian Wars. "At that same time Constantius took to wife Faustina, having long since lost Eusebia".
She was pregnant when Constantius died on 3 November 361 and later gave birth to their posthumous daughter, Constantia, the only child of the emperor. Constantia later married Emperor Gratian.
Widow
On 28 September 365 Procopius declared himself emperor in Constantinople, intending to depose the incumbent emperor Valens. The usurper's strongest claim to the throne was his kinship with the revered Constantinian dynasty, and he emphasized this link by keeping Faustina and her little daughter constantly near him in his public appearances.
From Wikipedia (CC BY-SA 4.0).