Villain in the story "Rappaccini's Daughter" by Nathaniel Hawthorne. Giacomo Rappaccini is a reclusive research physician in Padua, Italy. He lives with his daughter, Beatrice, who looks after his garden of rare and exotic plants. He is a doctor, but his colleague, Professor Pietro Baglioni, says 'that he cares infinitely more for science than for mankind.' His garden is filled with rare and exotic plants, and much of the story's action takes place there. However, all of the plants are poisonous, some so much that a touch is lethal. His obsession with gaining knowledge has pushed him to use these plants to dark purposes.
Rappaccini is considered to be a mad scientist, like Frankenstein, whose thirst to discover overrides his concern for morality, the safety of others, and the consequences of his research.