Castel is a surname. Notable people with the surname include:
Charles-Irénée Castel de Saint-Pierre (1658–1743), French writer
Jean-Gabriel Castel (born 1925), Canadian law professor
Louis Bertrand Castel (1688–1757), French mathematician
Moshe Castel (1909–1991), Israeli artist
P. Kevin Castel (born 1950), U.S. District Judge, Southern District of New York
René Richard Louis Castel (1758–1832), French poet and naturist
Robert Castel (1933–2013), French socilogist
