Some of his more notable performances include Money Train as a psychotic pyromaniac who terrifies toll booth operators, Lone Star in a rare leading role as a Texas sheriff charged with solving a decades old case, as Deputy Dwayne Looney in director Joel Schumacher's 1996 film A Time to Kill (based on the John Grisham novel), and in American Beauty as a homophobic Colonel of the United States Marine Corps (a role that garnered him a Best Supporting Actor Screen Actors Guild Award nomination). Cooper was nominated for another Screen Actors Guild Award, a BAFTA Award and won an Academy Award for Best Supporting Actor and a Golden Globe Award in 2003 for playing the role of John Laroche in Adaptation. Cooper also appeared in The Bourne Identity in 2002 as a ruthless CIA special ops director, a role he reprised (in flashbacks) in The Bourne Supremacy. He also had a supporting role as racehorse trainer Tom Smith in Seabiscuit, receiving another Screen Actors Guild Award nomination.
Cooper is often typecast as a government/military character and has played his share of low-key heroic types as well as villians.
Cooper was busy in 2005, having appeared in three well-received and acclaimed films: Jarhead (reuniting him with American Beauty director Sam Mendes and October Sky actor Jake Gyllenhaal), Capote and Syriana. He was in the thriller Breach, playing real-life FBI operative and spy Robert Hanssen. Cooper said that his belief was that Breach was the "first studio film where they've considered me the lead" actor.
He appeared as a government agent in dangerous territory alongside Jamie Foxx, Ashraf Barhom, Jennifer Garner and Jason Bateman in the action thriller The Kingdom. He also played Homer's father in October Sky.
Cooper has described his political views as "pretty left of left".