Johnsy is a character from the short story "The Last Leaf" by O. Henry. She is a young woman who becomes seriously ill with pneumonia and loses her will to live. As she lies in her bed, she fixates on the leaves of a vine outside her window, believing that when the last leaf falls, she will die. Throughout the story, Johnsy's condition reflects her emotional state, and her hope diminishes as the leaves drop. However, the actions of her neighbor, Behrman, who paints a leaf to give her hope, ultimately change her perspective and inspire her to fight for her life.