#1 Vivien Leigh
My favorite actress of all time would have to be Vivien Leigh because of her portrayal of Scarlett O'Hara in Gone with the Wind. She manages to take a very unlikeable character and turn her into a symbol of power and beauty. The movie is a masterpiece and a wonder to behold and she is at the center of it all, lighting up the screen with her amazing performance.
#2 Elizabeth Taylor
Elizabeth Taylor would be next because of her role as Cleopatra. This is another movie that is incredible and Elizabeth Taylor commands the screen. She dominates every moment on screen and really brings this historical figure to life.
#3 Loretta Swit
Because of her outstanding role in M*A*S*H (my favorite TV show of all time), I have to put her high on my list. She took a character that could have been cliche' (Hot Lips) and gave her tons of character and depth. Her character makes fascinating changes throughout the series and she has some of the best monologues of any tv actor.
#4 Keira Knightley
One of my favorite movies is Seeking a Friend at the End of the World, a very unrated film. She does a very moving performance in this that is very believable and touching.
#5 Kate Winslet
No... not for Titanic (sorry, but I'm not fond of Titanic)... but I really liked Kate Winslet in Eternal Sunshine of the Spotless Mind. This movie blows me away with its creativity and I think she does an interesting performance that always draws me in.
#6 Kathy Bates
I think Kathy Bates has done well with most of the roles she does but none are more incredible and frightening than in Misery. While Misery is not one of my favorite movies, her role in this terrified me and really made an impression.
#7 Scarlett Johansson
I have seen Scarlett Johansson in a lot of movies including Lost in Translation, Captain American, and Lucy. She always manages to hold her own and make an impression in guy dominated movies like the Avengers but I felt like she showed a lot of range in a movie like Lucy.
# 8 Hillary Swank
I have seen some really impressive performances by Hillary Swank, especially Million Dollar Baby. I haven't watched any of her movies recently but her performance was memorable enough to make this list.
#9, #10 (and #11) Female cast of the tv show Firefly, specifically Gina Torres, Morena Barracin and Jewel Staite. This was a short lived tv show but it has a strong following because of the strong plots and cast. I enjoyed many of the performances in this show and I thought the women were strong characters that were well acted. The show really gave women a chance to shine unlike some other sci fi shows where women seem more like secondary characters most of the time.