The younger brother of actor Ben Affleck, Casey Affleck spent the last few years of the 1990s working his way out of his brother's muscular shadow. The younger Affleck, who remarkably bears almost no resemblance to his older brother, was born August 12, 1975, in Falmouth, MA. He made his television debut in the 1987 American Playhouse special Lemon Sky and three years later played the young Robert Kennedy in the TV miniseries The Kennedys of Massachusetts.
The young actor's film debut came in 1995, with Gus Van Sant's To Die For, in which he had a supporting role as one of Joaquin Phoenix's slacker friends. The next year, he appeared in the largely unseen Race the Sun, and in 1997 benefited from the Power of Ben with roles in two of his brother's films. In the first, Chasing Amy, Affleck was little more than a blip on the screen, but in the second, Van Sant's Good Will Hunting, he had a decidedly more substantial part as one of Matt Damon's South Boston homeboys. Following the astounding, Oscar-winning success of Hunting, Affleck landed substantial roles in two films with casts featuring Who's Who lineups of Hollywood's Young and Hot: Desert Blue (1998), in which he starred with Christina Ricci, Kate Hudson, and Brendan Sexton III; and 200 Cigarettes (1999), in which he appeared as a soft-hearted punk alongside Desert Blue co-stars Ricci and Hudson, along with Paul Rudd, Courtney Love, Janeane Garofalo, and brother Ben. Although the film basically flopped, it did little to hurt the actor's career and the same year he attained added credibility with an unbilled appearance in the summer smash American Pie. The next few years found the younger Affleck in some notable more noticeable roles with his work in Hamlet, Committed, and Drowning Mona (all 2000). In 2001 he would get his largest billing yet, as well as his induction into the teen horror craze, with Soul Survivors.
A re-teaming with Good Will Hunting co-horts Van Sant and Damon in 2002's deliberate independent drama Gerry was bookended by sizable supporting roles in director Steven Soderbergh's carefree crime comedies Ocean's Eleven and Ocean's Twelve, and in 2005 the younger Affleck would prove without question his ability to carry a dramatic feature with his subtle portrayal of an aimless twenty-something hindered by familial obligations in Steve Buscemi's Sundance-nominated drama Lonesome Jim. In 2006 Casey would star opposite Zach Braff in director Tony Goldwin's romantic comedy re-make The Last Kiss.
2007 would prove to be a turning point for the actor. In addition to reprising his character for the third installment of the Ocean's Eleven franchise, Affleck earned strong reviews for two drama that year. He headlined brother Ben Affleck's directorial debut, an adaptation of Dennis Lehane's Gone Baby Gone, bring to life the character of Patrick Kenzie, a private eye with close ties to the mean streets of Boston. But his work as the title coward in The Assassination of Jesse James by the Coward Robert Ford brought him numerous good reviews even though the film failed to make much of a splash at the box office. His work earned him a number of year-end accolades including nominations from the Academy and the Screen Actors Guild for Best Supporting Actor (even though he is the lead).
After these critical successes he was poised for a breakthrough, but he was away from the big screen for three years, not returning to movies until 2010 as the star of the Jim Thompson adaptation The Killer Inside Me, and as director/producer/screenwriter/editor of I'm Still Here, a mockumentary that satirized celebrity meltdowns starring Joaquin Phoenix. He was part of the ensemble in Tower Heist the next year, and followed that up by voicing a part in ParaNorman in 2012.