Gaius Vibius Trebonianus Gallus (206 – August 253) was Roman emperor from June 251 to August 253, in a joint rule with his son Volusianus.
Gallus was born in Italy, in a family with respected Etruscan senatorial background. He had two children in his marriage with Afinia Gemina Baebiana: Gaius Vibius Volusianus, later emperor, and a daughter, Vibia Galla. His early career was a typical cursus honorum, with several appointments, both political and military. He was suffect consul and in 250 was made governor of the Roman province of Moesia Superior, an appointment that showed the confidence of Emperor Decius in him.
Rise to power
In June 251, Decius and his co-emperor and son Herennius Etruscus died in the Battle of Abrittus at the hands of the Goths they were supposed to punish for raids into the empire. According to rumours supported by Dexippus (a contemporary Greek historian) and the thirteenth Sibylline Oracle, Decius' failure was largely owing to Gall