I'm so old I remember when Jean Shrimpton was the most beautiful/sexiest. (and she was!)
If we're going by photographs, Liz Taylor, Jacquline Smith, Marilyn Monroe, the one who played Wonder Woman, Bridget Bardo, Maureen O'Hara, My Mother, Myrna Loy.
If you ask freshmen boys who've just studied Romeo & Juliet, Olivia Hussey.