This may be at the top of the list. If not, it's competing for it.
One of the great performances in the history of Broadway is when Mary Martin starred as Nellie Forbush in Rodgers & Hammerstein's South Pacific, which opened in 1949. However, when the movie was made, Mitzi Gaynor was hired for the role instead, one of many unfortunate choices for that film, I think. The larger problem is that Mary Martin's legendary performance was lost. There's the cast album, and a video from, I believe, a TV appearance with co-star Ezio Pinza on The Ed Sullivan Show. The performance is gone.
Sort of. But it's close enough. This doesn't come from that 1949 Broadway production, but three years later South Pacific opened in London on the West End, and Mary Martin famously went with the production to re-created her classic role.
And for reasons I don't begin to understand, but am forever grateful, much of that production was filmed!
There's more to come in later videos, but this is the opening 10 minutes of the show. And an impressive 10 minutes, it is. It includes the songs, "Dites-Moi," "A Cockeyed Optimist," and "Twin Soliloquies," sung with baritone Wilbur Evans. It's particular fun to see how Mary Martin's entrance is not only delayed, but the audience is a bit teased with it. And when she does finally appear, even the generally-reserved British audiences for 1952 give her an appreciative welcome.
By the way, there's a tale behind why the song with the character of Emil De Becque is a "Twin Soliloquy" and not a duet. When Metropolitan Opera star Ezio Pniza was hired for the original Broadway production, Mary Martin went to Rodgers and Hammerstein and made clear that in no way would she sing with him -- it wasn't personal, it was that she knew that as operatic as her contralto voice was, it was no match for a true opera singer, and that she'd be drowned out and come across poorly. So, they structured all the songs the two perform together in a way that, though they are singing the same numbers, they are always separate. In this particular case, twin soliloquies. It will be clear when you see the scene.
And that we have this scene to see (and others to come) is just utterly remarkable.
Here then, is 10 minutes of true theater history. Curtain -- literally -- up.