Christopher Eugene O'Donnell (born June 26, 1970) is an American actor. After modeling and acting in numerous commercials as a teenager, he made his film debut in the comedy-drama film Men Don't Leave (1990). Following supporting roles in the films Fried Green Tomatoes (1991) and School Ties (1992), O'Donnell had his breakout with a starring role in the drama film Scent of a Woman (1992), which earned him a nomination for the Golden Globe Award for Best Supporting Actor – Motion Picture. After starring roles in the films The Three Musketeers (1993) and Circle of Friends (1995), O'Donnell received further mainstream recognition for his role as Dick Grayson / Robin in the DC Comics superhero films Batman Forever (1995) and Batman & Robin (1997), as well as his portrayal of writer Ernest Hemingway in the romantic drama film In Love and War (1996). In the 2000s, O'Donnell starred in the films Vertical Limit (2000), Kinsey (2004), and Kit Kittredge: An American Girl (2008), and had a main role as Jack McAuliffe in the TNT television miniseries The Company (2007). O'Donnell starred in the main role of G. Callen on all fourteen seasons of the CBS police procedural series NCIS: Los Angeles (2009–2023). He also starred in the spy comedy film Cats & Dogs: The Revenge of Kitty Galore (2010), and has a main role as Don Hart on the ABC series 9-1-1: Nashville (2025–present).