Gaspare Aselli (or Asellio) (c. 1581–14 April 1626) was an Italian physician noted for the discovery of the lacteal vessels of the lymphatic system. Aselli discovered (or rediscovered) the chylous vessels, and studied systematically the significance of these vascular structures.
He was born in Cremona, and became professor of anatomy and surgery at the university of Pavia. He later practised medicine in Milan, where he died. His description of the lacteals, De lactibus sive Lacteis venis, was published in 1627 at Milan.