Film lends itself more to these type of lists since we can actually go back and watch those performances. It's pretty much impossible to do it for Broadway. There's legendary performances: Ethel Merman in GYPSY, Angela Lansbury in MAME and SWEENEY TODD, Bea Arthur in MAME, Joel Grey in CABARET, Laurette Taylor in THE GLASS MENAGERIE, the cast of A STREETCAR NAMED DESIRE, Sidney Poitier in A RAISIN IN THE SUN. There's more contemporary ones that people always bring up: Natasha Richardson and Alan Cumming in CABARET, Donna Murphy in PASSION, Audra McDonald in CAROUSEL, Cherry Jones in THE HEIRESS and DOUBT, Christine Ebersole in GREY GARDENS, Jennifer Holliday in DREAMGIRLS, Raul Julia and Anita Morris in NINE, Kelly Bishop in A CHORUS LINE, Bernadette Peters and Mandy Patinkin in SUNDAY IN THE PARK WITH GEORGE, etc. So hard to actually track every single one of those down.
The highlights from what I've actually seen live:
Amy Morton in AUGUST: OC
Amy Morton and Tracy Letts in WHO'S AFRAID OF VIRGINIA WOOLF?
Christine Ebersole and Mary-Louise Wilson in GREY GARDENS
Laura Benanti in GYPSY
Geoffrey Rush in EXIT THE KING
Liev Schreiber, Jessica Hecht and Scarlett Johansson in A VIEW FROM THE BRIDGE
Cherry Jones in THE GLASS MENAGERIE
Sophie Okonedo and Anika Noni Rose in A RAISIN IN THE SUN
Audra McDonald in LADY DAY AT EMERSON'S BAR & GRILL
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"