How about Joan Crawford, who was good when she was young (above, topmost) but who morphed into a complete genius in middle age (above). How do you like this combination of a slip, a near-unibrow, and an aesome awning-stripe background?
I sneaked this (above) in after I got comments reminding me that I left out Garbo. I should be flogged for that because I love Garbo. Amazingly, I didn't always feel that way. Before two or three years ago I used to wonder what all the fuss was about. What turned me around was that I finally got hold of a good print of "Grand Hotel." Watch that, "Anna Christie" and "Romance" and you'll see for yourself why she was so special. She's one of the queens of sentimental over-the-top.
And let us not forget Madeline Kahn who was brilliant as Eunice in "What's Up, Doc?"
Imogene Coca (above, spelled right this time), the wonderful partner of Sid Ceasar in the 50s!
Come on, no screen witch matched Margaret Hamilton, though the woman who did the voice of the hag in Disney's "Snow White" wasn't shabby.