Aulus Didius Gallus was a Roman general and politician of the 1st century AD.

He was consul in AD 36 and probably led the cavalry forces during Emperor Claudius' invasion of Britain in AD 43. He later campaigned in the Crimea and became proconsul of Asia.

He was made governor of Britain in AD 52, inheriting the post from Ostorius Scapula at a time when the situation was deteriorating as a result of a string of rebellions.

Didius acted to quell the rebels rather than enlarge the empire during his rule which lasted until AD 57. Although criticised by Tacitus as being reactive and defensive, he was probably acting on instructions from Claudius who did not consider the benefits of further conquest in difficult terrain to be great enough to warrant the risk. Instead, Didius built roads and forts at the borders such as those at Usk to contain the barbarians.

Venutius' first insurrection against Queen Cartimandua of the Brigantes occurred during Didius' rule and he despatched troops to aid her. Didius was replaced by Quintus Veranius.