In classic moviestars it's:
1. Audrey Hepburn
2. Greta Garbo
In tv-stars its:
1. Veronica Hamel
2. Bernadette Peters (I know she's made a lot of movies, but I know her mostly from tv. And she was a hot little minx.
3. Amanda Tapping
4. Jeri Ryan
5. Hayley Atwell
Modern Movies:
1. Scarlett Johansson
2. Kristen Stewart
3. Emma Watson
4. Blake Lively
All above is purely judged by their looks, not acting skills.