Dr. Sam Beckett is a fictional character from the television series Quantum Leap, which aired from 1989 to 1993. He is a physicist who invents a time-travel experiment called Quantum Leap, allowing him to leap into the bodies of people at different points in time. His goal is to correct historical mistakes and improve their lives. Throughout the series, Dr. Beckett is accompanied by his best friend, Al Calavicci, who appears as a hologram to provide guidance and information. The show explores themes of morality, friendship, and the impact of individual choices on history.