Muse (source of inspiration) in the context of "Sweet Charity"

Kathleen Irene Ashburnham Newton (née Kelly; 1854–1882) was an Irish-British model, best known for her many sittings with the French artist James Tissot. Her artistic relationship with Tissot quickly turned into a romantic one, and the two lived together, representing themselves as a married couple, for the rest of her life, which was cut short by tuberculosis. She modeled for Tissot constantly throughout their time together, and Tissot's biographers remembered her as his muse.

Although Tissot's contemporary audience understood his relationship with Newton, biography published during his lifetime did not mention her, and magazine coverage of his work only discussed her obliquely. Tissot referred to her by pseudonyms like la mystérieuse (the mysterious) and la belle irlandaise (the Irish beauty) in the titles of his paintings. His biographers started including her in his story soon after he died in 1902, referring to her by a nickname, Kitty, that he had used. Her full identity entered the historical record in 1954, when her niece Lilian Hervey answered a journalist's plea for information about her.

Nancy Clara Cunard (10 March 1896 – 17 March 1965) was a British writer, heiress and political activist. She was born into the British upper class, and devoted much of her life to fighting racism and fascism. She became a muse to some of the 20th century's most distinguished writers and artists, including Wyndham Lewis, Aldous Huxley, Tristan Tzara, Ezra Pound and Louis Aragon—who were among her lovers—as well as Ernest Hemingway, James Joyce, Constantin Brâncuși, Langston Hughes, Man Ray and William Carlos Williams. MI5 documents reveal that she was involved with Indian diplomat, orator, and statesman V. K. Krishna Menon.

In later years she suffered from mental illness, and her physical health deteriorated. When she died in the Hôpital Cochin, Paris, she weighed only 26 kilograms (57 pounds; 4 stone 1 pound).