In the dangerous world of ancient Roman politics, power did not always come from armies or speeches in the Senate. Sometimes, it came from a small vial of poison. In Ancient Rome, assassinations were practically part of the fabric of society. In the 1st century CE, as the Empire became one of the most powerful civilizations in human history, one woman became the most feared figure connected to this shadowy side of Roman life: Locusta. Though not a general or a politician, Locusta became infamous as one of the most notorious assassins in Roman history.
Not much is known about Locusta the Gaul, aside from where she was from, before the writings of Cassius Dio, Suetonius, and Tacitus, imperial Roman historians who recorded her name in their texts. Locusta came from what is now France, or Gaul to the Romans, and had clearly mastered the arts and sciences of herbology, toxicology, and botany. It is not known if she was summoned to Rome or had come to seek her fortune in Rome on her own, or had been brought to Rome against her will as a slave or wife. All that is explicitly established is that Locusta made a name for herself as a poisoner and quickly rose through the ranks to the imperial court.
In 54CE, Locusta was in jail for poisoning (who she poisoned or why is unknown), but was sought out by Agrippina the Younger, the great-granddaughter of Emperor Augustus Caesar and fourth wife to Emperor Claudius, to help poison the emperor himself. Locusta gave the Empress Atropa Belladonna, a very toxic nightshade that was said to have been administered to Claudius’s food. The murder itself is traditionally credited to the emperor’s doctor, but may have been aided by Locusta’s toxicology knowledge. Agrippina’s son and Claudius’s adopted heir, Lucius Domitius, or Nero, came to power following his stepfather’s death, and he, like his mother and advisor Agrippina, saw Locusta as a useful ally.
Locusta was still in prison when, in 55CE, Nero himself had Locusta brought to him. He asked her to help him poison his stepbrother, Claudius’s teenage son from his third marriage, Tiberius Claudius Caesar Britannicus. The boy was the only true threat to Nero’s claim to the throne as the direct male offspring of Claudius. Locusta gave the emperor a potent poison of arsenic, hellebore, mandrake, and belladonna, but Britannicus survived the attempt. Having failed to kill the boy, Nero personally flogged Locusta, threatening to execute her if she did not provide a stronger poison that would swiftly end the child’s life, so Locusta obeyed.
Nero had a hot beverage, which had been taste-tested beforehand, served to his stepbrother. Because it was too hot to drink, untested water laced with poison was added to cool it down before it was given to the boy. The almost fourteen-year-old teenager drank his drink and died almost immediately, suffering a gruesome fit in front of the shocked court. Nero was delighted by the outcome of Locusta’s poison and, as a reward for her service to him, pardoned her of all previous crimes, giving Locusta estates and a trove of wealth and gifts. He considered her his instrumentum regni, or instrument of rule, making her his personal poisoner and a teacher for assassins, who would learn the science of plants and how to use their toxicity to advantage.
Locusta now had the protection of the emperor and a means to live incredibly comfortably, something she may never have experienced before. She served as his personal assassin for his reign, helping to eliminate slaves and nobles alike with untraceable and unnoticeable poisons. She is credited with helping the emperor kill many of his adversaries.
In 68CE, after Nero fled from Rome during the Senate-led rebellion against him (he was credited with terrorizing his people, killing indiscriminately, including his mother, and for doing nothing during the Great Fire of Rome in 64CE), Nero killed himself. Locusta suddenly found herself without any safeguard or means to protect herself from the fury of Nero’s enemies. Nero’s successor, Emperor Servius Sulpicius Galba, had her and several other allies of Nero arrested, paraded through the streets of Rome, and publicly executed in 69CE.
Much of Locusta’s life remains a mystery, but her reputation as Rome’s most infamous poisoner has endured for nearly two thousand years. Whether she was a ruthless criminal or a tool for powerful rulers, her story reveals the darker side of Roman politics, where ambition, betrayal, and murder often determined the fate of emperors.
In a society that largely excluded women from formal power, Locusta wielded influence from the shadows. Whatever the truth behind her actions, her legacy remains a chilling reminder that in imperial Rome, a single dose of venenum could change the course of history.
Bibliography:
Athanasiou, Christina. “Locusta of Gaul: The Imperial Poisoner of Ancient Rome.” Roman Empire Times. May 22nd, 2024.
Tacitus, Publicus Cornelius. “The Annals.” Archive. Translated by John Jackson. October 1st, 2023.
Tranquillus, Gaius Suetonius. “The Lives of the Twelve Caesars.” Chicago University. Edited and Translated by Bill Thayer. Updated October 31st, 2017.
