The 7th Voyage of Sinbad (1958)
The 7th Voyage of Sinbad is the film where Ray Harryhausen invented the modern fantasy adventure. Kerwin Mathews plays Sinbad.
Torin Thatcher played the magician Sokurah in The 7th Voyage of Sinbad, and the character’s malevolence is the film’s engine. He was British, taught school before acting, and had a substantial stage career.