Dr. Abby Lockhart is a fictional character from the television series ER, which aired from 1994 to 2009. She is portrayed by actress Maura Tierney and serves as an attending physician in the emergency department of Chicago's County General Hospital. Abby is known for her strong work ethic, compassion for patients, and complex personal life. Throughout the series, Abby faces various challenges, including her relationships with colleagues like Dr. Luka Kovac and her struggles with her own mental health. Her character evolves significantly, showcasing her growth as a doctor and a person over the show's 15 seasons.