William Gaither "Billy" Crudup (pron.: /ˈkruːdəp/; 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 Prince 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.