Evelyn Nesbit is another character (like Harry Houdini) that is lifted straight from the pages of the history books.
Evelyn Nesbit was sort of the first supermodel. Her face was everywhere, on products and in newspapers and the subject of numerous paintings. As Emma Goldman tells her, she is the reason a laborer "dreams not of justice but of being rich" (11.3). Why would you dream of justice when you could dream of being rich enough to have a girlfriend like Evelyn Nesbit?
In the novel, we're introduced to Evelyn as the "Trial of the Century" begins. Evelyn's husband, Harry K. Thaw, has shot and killed the famous architect Stanford White, who used to be Evelyn's lover. Evelyn was born poor but she stands to gain a lot of money through her marriage to Thaw, both for her testimony at trial and her divorce. It's every woman for herself at this point: Evelyn wants to be self-sufficient.
But after her affair with Younger Brother comes to light, Evelyn gets only a small percentage of what she thought she'd get from Shaw (who ends up going to a hospital for the criminally insane).
Evelyn starts out as a woman who gets she wants because of her looks. But, like Mother, she changes and grows in the novel… just not as much. Through her involvement with Tateh and Little Girl, she meets Emma Goldman, and begins to see her life as shallow and her marriage to Thaw as a sort of gilded prostitution. She also realizes she's more than just a pretty face.
She begins to donate much of her money to socialist causes, and by the end of the novel has "lost her looks and faded into obscurity" (40.24) though it no longer seems like she wants the attention anyway.