Roman Emperor Valentinian I made his brother, Flavius Valens, his co-emperor.

Flavius Valens was the younger brother of Valentinian I born in 328 AD at Cibalae in Pannomia. Following the death of the Emperor Jovian, Valentinian I was proclaimed Emperor and in return he raised his brother Valens to the rank of co-Emperor. Valens thus became Emperor of the Eastern provinces.