Abby Lockhart is a fictional character from the television series ER, which aired from 1994 to 2009. Portrayed by actress Maura Tierney, Abby is introduced as a nurse and later becomes a medical resident. She 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 family background. Her character development highlights themes of resilience and the emotional toll of working in a high-pressure medical environment.