AR Antoninianus, A.D. 252, Rome, 21.3mm, 3.43g, 180°, RIC IV 32; scarce.
Obv: IMP CAE C VIB TREB GALLVS AVG. Radiate, draped and cuirassed bust right.
Rev: APOLL SALVTARI. Apollo standing left, branch in right, leaning with left on lyre set on rock.
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Gaius Vibius Afinius Trebonianus Gallus Augustus, also known as Terbonianus Gallus, was Roman Emperor from 251 to 253, in a joint rule with his son Volusianus. His early career was typical, with several appointments, both political and military. In 250 he was nominated governor of the Roman province of Moesia Superior, an appointment that showed the confidence of Emperor Trajan Decius in him. In Moesia, Gallus was a key figure in repelling the frequent invasion attacks by the Gothic tribes of the Danube and became popular with the army.

In June 251, Decius and his co-emperor and son Herennius Etruscus died in the Battle of Abrittus. The soldiers proclaimed Gallus emperor, despite Hostilian, Decius' surviving son, ascending the imperial throne in Rome. Gallus was on good terms with Decius' family, and while he did not back down from his intention to become emperor, he did accept Hostilian as co-emperor with the approval of the Senate. Hostillian though died of plague soon after.

Gallus had a difficult reign plagued by revolts and by invasions of Persians and Goths. Aemilianus, now governor of Moesia, took the initiative and defeated the Gothic invaders. The army was not pleased with Gallus and proclaimed Aemilianus emperor. Gallus recalled his remaining troops to Rome, under the command of future emperor Licinius, and prepared to fight the usurper. The details of what happened are not entirely clear. Some sources claim that after an initial defeat, he and his son Volusian were murdered by their own troops, other sources claim that Gallus' troops defected before any battles took place. In any event, both Gallus and Volusian were killed in August of 253.