George Clooney won a best supporting actor Oscar for his role in which film of the 2000s?

Clooney won the Academy Award for Best Supporting Actor for his role as Bob Barnes in Syriana and Gaghan's script was nominated by the Academy for Best Original Screenplay.

Syriana is a 2005 American geopolitical thriller film written and directed by Stephen Gaghan, and executive produced by George Clooney, who also stars in the film with an ensemble cast. Gaghan's screenplay is loosely adapted from Robert Baer's memoir See No Evil. The film focuses on petroleum politics and the global influence of the oil industry, whose political, economic, legal, and social effects are experienced by a Central Intelligence Agency operative (George Clooney), an energy analyst (Matt Damon), a Washington, D.C. attorney (Jeffrey Wright), and a young unemployed Pakistani migrant worker (Mazhar Munir) in an Arab state in the Persian Gulf. The film also features an extensive supporting cast including Amanda Peet, Tim Blake Nelson, Mark Strong, Alexander Siddig, Amr Waked, and Academy Award winners Christopher Plummer, Chris Cooper and William Hurt.