Stefano Delle Chiaje was an Italian zoologist, botanist, anatomist and physician.
Delle Chiaje studied medicine in Naples, where he was a pupil of Giuseppe Saverio Poli. Together they started compiling books on the bivalves and the gastropod molluscs of the Kingdom of the Two Sicilies. He later taught pathology and performed research in the field of malacology. He erected the genus of nemertean worms Polia, naming it in honour of Poli, and described Polia lineata and Polia siphunculus. The latter has since been synonymised with Cerebratulus marginatus, but Delle Chiaje's description shows an understanding of the animal's anatomy and recognition of its constituent parts that was missing among many of his contemporaries.
He made a study of the skeletons and detached bones found during the excavations of the buried city of Pompeii, making deductions on the health of the population, their characters and occupations, the types of injuries they suffered and the skill of their surgeons.
He is also remembered for his research in the field of botany, especially medicinal plants, and of zoology, with particular reference to the taxonomy of invertebrates of the Kingdom of Naples.