Trebonianus Gallus (Latin: Gaius Vibius Afinius Trebonianus Gallus Augustus; 206 – August 253), also known as Gallus, was Roman Emperor from 251 to 253, in a joint rule with his son Volusianus.

Gallus was born in Italy, in a family with respected ancestry of 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 nominated governor of the Roman province of Moesia Superior, an appointment that showed the confidence of Emperor Trajan Decius in him.

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 Gallus, who had conspired with the invaders. In any case, when the army heard the news, the soldiers proclaimed Gallus emperor, despite Hostilian, Decius' surviving son, ascending the imperial throne in Rome. This action of the army, and the fact that Gallus seems to have been on good terms with Decius' family, makes Dexippus' allegation improbable. Gallus did not back down from his intention to become emperor, but accepted Hostilian as co-emperor, perhaps to avoid the damage of another civil war.

...
Wikipedia