Junia referred to by modern historians as Junia Secunda was a Roman woman who lived in the 1st century BC. She was the second daughter of Servilia Caepionis, the lover of Julius Caesar and sister of Cato the Younger, and Decimus Junius Silanus, the elder being Junia Prima and the younger Junia Tertia. She was the half-sister of Marcus Junius Brutus, the most famous of Julius Caesar's assassins. She married Marcus Aemilius Lepidus who was a member of the Second Triumvirate, along with Mark Antony and Octavian (Later Augustus).
In 50 BC, Cicero claimed that Junia was unfaithful to Lepidus, that her portrait being found among the chattels of the debauchee Vedius, and expresses his surprise at her brother and husband taking no notice of her conduct. However some have argued that it was Junia Prima, rather than Junia Secunda, who had the affair with Vedius. Junia was part of a plot to kill Octavian, formed by her son Lepidus the Younger, after the battle of Actium, however it was foiled.