Giulia Tofana (also spelled Toffana, Tophana, Tophania) (died in Rome, 1651) was an Italian professional poisoner. She sold a poison called Aqua Tofana (supposedly invented by Thofania d'Adamo, who may have been Giulia's mother) to women who wanted to murder their husbands.

Giulia Tofana was a 17th-century professional poisoner who sold her signature concoction to wives that wanted to kill their husbands. Once she was caught, Tofana guessed that she was responsible for having provided the poison in 600 deaths which, in a way, made her one of the most prolific assassins in history.