In 1950 Charlton Heston made his major motion picture debut in DARK CITY opposite seasoned pro Lizabeth Scott . Heston, of course, went on to be one of Hollywood's most enduring stars. Like Lizabeth , Hal Wallis gave Heston star billing in his very first picture. Hal's many talents as a filmmaker was a keen casting sense, particularly for men. Aside from all those guys at Warners, he found Burt Lancaster, Kirk Douglas, and then, fortunately, me.
Talent is a factor, so is looks.
Neither is crucial. There are a number of major stars who are not overwhelmingly attractive, many others who couldn't conceivably act on stage. Never mind what you think . If the camera doesn't love her, forget it. You can't determine this in advance, either.