William Gaither "Billy" Crudup ( born July 8, 1968) is an American actor of film and stage. He is well known for his roles as guitarist Russell Hammond in Almost Famous
, Will Bloom in Big Fish
, and Ashitaka in Princess Mononoke. He also starred in the 2007 romantic comedy film Dedication
, alongside Mandy Moore. In 2009, he appeared as Doctor Manhattan in the film Watchmen
and as J. Edgar Hoover in the film Public Enemies.