The main characters in 'The Immortal Life of Henrietta Lacks' are Henrietta Lacks herself, whose immortal HeLa cells revolutionized medical research, and her family, particularly her daughter Deborah Lacks. Henrietta, an African American woman, unknowingly contributed her cells to science when they were taken without her consent during her cancer treatment in the 1950s. Her cells became the first human cells to survive and multiply outside the body, leading to groundbreaking discoveries. Deborah, who never knew her mother, becomes a central figure as she seeks to understand her mother's legacy and the ethical implications of her cells' use. The book also highlights the scientists who worked with HeLa cells, like George Gey, and the journalists, including the author Rebecca Skloot, who brought Henrietta's story to light.