AFAIK, the following are all natural and hot:
Nicole Kidman
Lindsay Lohan (pre-skank she was hot)
Molly Ringwald (possibly - some say she’s really a brunette or at least auburn)
Alicia Witt
Alyson Hannigan
Angie Everhart
Laura Prepon (I think she’s a natural redhead)
Julianne Moore
Alyson Hannigan is definitely sometimes much more red-haired than others.
Since I am a granny, I can’t speak to the charge that they are hot. Half of them I never heard of but I will agree that Julianne Moore is a truly beautiful woman.
The most famous red-headed movie star of all is...... MAUREEN O’HARA.