Siro Marcellini is an Italian film director and screenwriter known for his work in the mid-20th century. Born in Genzano di Roma, he began his career as a theater director before transitioning to film, initially serving as an assistant director. Marcellini directed eleven films between 1953 and 1970, often contributing to the screenplays. His notable works include The Devil's Cavaliers (1959), The Beast of Babylon Against the Son of Hercules (1963), and Gangsters' Law (1969). Marcellini's films are characterized by their engagement with popular genres of the time, including adventure and crime.