Jean-Charles de la Faille or Jan-Karel della Faille (Antwerp, March 1, 1597 - Barcelona, November 4, 1652) was a Flemish Jesuit mathematician.

He was born in Antwerp, part of the Spanish Empire at that time, where he was educated by the Jesuits, whose order he joined in 1613. He then went to a Jesuit college in Mechelen for two years. Afterwards, he came back to Antwerp where he became a disciple of Grégoire de Saint-Vincent. In 1620, he went to Dole, also part of the Spanish Empire, to teach mathematics and learn theology.

From 1626 to 1628, he taught mathematics at the Jesuit college of Leuven, before being appointed to the Imperial College in Madrid. He there advised Philip IV, king of Spain, on military questions, specially fortifications, and taught mathematics as well.

His most famous book is Theoremata de centro gravitatis partium circuli et ellipsis (1632) in which he determined the centre of gravity of the sector of a circle, for the first time. At the request of della Faille's family, the Flemish painter Anthony van Dyck painted a portrait of the mathematician in 1629. The portrait shows the mathematician in his Jesuit outfit with a set of tools (including a compass, a t-square and a globe).
He died in Barcelona, aged 55.