Caleb Casey McGuire Affleck-Boldt (born August 12, 1975) is an American actor and filmmaker. He is the recipient of various accolades, including an Academy Award, a British Academy Film Award, a Golden Globe Award and a Satellite Award. He began his career as a child actor, appearing in the PBS television film Lemon Sky (1988) and the miniseries The Kennedys of Massachusetts (1990). He later appeared in three Gus Van Sant films: To Die For (1995), Good Will Hunting (1997), and Gerry (2002), and in Steven Soderbergh's comedy heist trilogy Ocean's Eleven (2001), Ocean's Twelve (2004), and Ocean's Thirteen (2007). His first leading role was in Steve Buscemi's independent comedy-drama Lonesome Jim (2006).

Affleck's breakthrough came in 2007, when he was nominated for the Academy Award for Best Supporting Actor for his performance in the Western drama The Assassination of Jesse James by the Coward Robert Ford and starred in the crime drama Gone Baby Gone, directed by his brother Ben Affleck. In 2010, he directed the mockumentary I'm Still Here. He then had a string of successful films in the early 2010s, including Tower Heist (2011), ParaNorman (2012) and Interstellar (2014), and received particular praise for his performance as an outlaw in the indie film Ain't Them Bodies Saints (2013).

In 2016, Affleck starred in the drama film Manchester by the Sea. For his performance as Lee Chandler, a man grieving the loss of his children and his brother, he received universal acclaim and won the Critics' Choice Movie Award, Golden Globe Award, British Academy Film Award and Academy Award for Best Actor, and received a Screen Actors Guild Award nomination. In 2017, Affleck received critical acclaim for his leading role in the supernatural drama film A Ghost Story.