Conversation so far:
When did Jeanette MacDonald start musical theatre?
In November 1919, Jeanette MacDonald joined her older sister Blossom in New York and landed a job in the chorus of Ned Wayburn's The Demi-Tasse Revue.
What did Jeanette MacDonald do in the theatre?
Jeanette MacDonald landed a job in the chorus of Ned Wayburn's The Demi-Tasse Revue.
Did Jeanette MacDonald win any awards?
Jeanette MacDonald was crowned as the Queen of the Movies in 1939 with Tyrone Power as her king. She was named Philadelphia's Woman of the Year in 1961.
Are there any other interesting aspects about Jeanette MacDonald besides her early broadway career and awards?
Jeanette MacDonald's production of The King and I opened August 20, 1956, at the Starlight Theatre. While performing there, she collapsed.
Did Jeanette MacDonald survive her collapse during the production of The King and I in 1956?
Officially, Jeanette MacDonald's collapse was announced as heat prostration, but in fact it was a heart seizure. She began limiting her appearances.
Did Jeanette MacDonald continue to perform after her collapse during the production of The King and I in 1956?
Jeanette MacDonald began limiting her appearances and a reprisal of Bitter Sweet in 1959 was her last professional appearance.

Question: What was her most famous act?
Self-contained rewrite: What was Jeanette MacDonald's most famous act?