Locusta or Lucusta, was a notorious maker of poisons in the 1st-century Roman Empire, active in the final two reigns of the Julio-Claudian dynasty. She supposedly took part in the assassinations of Claudius and Britannicus. She was a favourite of emperor Nero for several years, and Nero had her provide training to other poisoners in his service. Following Nero's death, Locusta was executed by his successor, Galba.