Living in your brother's shadow for a decade is decent prep for playing a man obsessed with fame. When Andrew Dominik cast him as Robert Ford in The Assassination of Jesse James by the Coward Robert Ford, he noted Casey understood firsthand what it felt like to never be the main attraction. The 1997 role in Good Will Hunting (where the supporting Morgan role had been written for him) gave him visibility without momentum. The year 2007 changed that: he filmed Jesse James and Gone Baby Gone back to back, earning an Oscar nomination for the first while an NYT critic wrote of the second: 'I'm not sure exactly when Casey Affleck became such a good actor...'
The 2017 Best Actor Oscar for Manchester by the Sea should have been his defining moment. The ceremony gave the world a different image: Brie Larson didn't applaud when he won, a deliberate gesture toward the two sexual harassment lawsuits he settled out of court in 2010. Both suits came from the production of I'm Still Here and alleged a hostile work environment. The settlement terms stayed confidential. His 2018 response called his behavior 'unprofessional' without addressing any specifics. Christopher Nolan still cast him in Oppenheimer (2023). A meaningful segment of the press hasn't moved on.
The Joaquin Phoenix arc is a whole movie. They met on To Die For in 1995, got matching tattoos in Italy, shared apartments, and Phoenix eventually introduced him to his sister Summer, who Casey married in 2006. That friendship underwrote I'm Still Here, the mockumentary where Phoenix 'quit acting to become a rapper' and stayed in character for over a year. When the harassment lawsuits hit, Phoenix's lawyers reportedly told him to stay silent. Summer filed for divorce in 2017. By 2019, Phoenix told Vanity Fair he hadn't spoken to Casey in 'many years.' The project that was supposed to be their artistic statement ended both the marriage and the friendship.