He was often typecast as a Mexican bandit in paella and spaghetti westerns, including The Big Gundown (directed by Sergio Sollima), A Pistol for Ringo and Return of Ringo (directed by Duccio Tessari), Arizona Colt (directed by Michele Lupo), Minnesota Clay (directed by Sergio Corbucci), and Sartana (directed by Gianfranco Parolini). Though (almost) always given the same role — a Mexican bandit chief — Sancho was a strong actor, and became one of the icons of these films.
He also appeared in a number of Spanish horror movies in the '60s and '70s. One of the better known horror parts was the role of a corrupt small town mayor in El Ataque de los Muertos sin Ojos (AKA Return of the Blind Dead), directed by Amando de Ossorio. Another notable horror film was Orloff and the Invisible Man (1971), directed by Pierre Chevalier and starring Howard Vernon, an unofficial continuation of the Dr. Orloff saga begun by Jess Franco in The Awful Dr. Orloff (1962). Sancho also turned up briefly in the epic Lawrence of Arabia playing the Turkish sergeant who arrests T. E. Lawrence in Deraa.
It is possible that Fernando Sancho's mother was Greek; he could certainly speak Greek trippingly, and acted in several Greek movies, all depicting moments of Greek martial history.
Sancho had a very prolific career and remained active in film up to his death. He made larger than life characters his specialty, and was a similarly 'big' character off screen as well — popular both with audiences, and with his fellow actors.