Cosimo Fancelli (c.1620 – 3 April 1688) was an Italian sculptor of the Baroque period, active mainly in Rome. He was the son of the artist Carlo Fancelli from Arezzo. Like his brother, the sculptor Giacomo Antonio Fancelli, he began his career as an assistant in the studio of Bernini. He is said to have helped sculpt the figure of the Nile in the Fountain of the Four Rivers at Piazza Navona, though this is also attributed to his brother Giacomo.