It seems to me that the only person who satisfies all or most every one's interpretations of "legend" is Ethel Merman. She originated many wonderful roles, she always "found her way back to the stage", and for the most part (at least more than most of the other women mentioned) she achieved some reknown outside of the theatre world. (Hell, she had to be well-known enough to have been spoofed in Airplane!)
And what about the men?
Rex Harrison! Zero Mostel! John Raitt! Joel Grey!
"This is what I trained to do, and this is what I love about theater. What I love about being an actress is being able to really look into myself and understand another human being. And out my own self, to shape and form and fashion a real human being--and to present that in such a way that people see something of themselves or their own understanding in that human being."
--Phylicia Rashad