Rockwell has also received positive notices for his role opposite Nicolas Cage in Ridley Scott's "Matchstick Men" (2003), with "Entertainment Weekly" calling him "destined by a kind of excessive interestingness to forever be a colorful sidekick." He received somewhat more mixed reviews as Zaphod Beeblebrox in the film version of "The Hitchhiker's Guide to the Galaxy" (2005). He then had a notable supporting role as Charley Ford, brother of Casey Affleck's character Robert Ford, in the well-received drama "The Assassination of Jesse James by the Coward Robert Ford" (2007), in which Brad Pitt played the lead role of Jesse James. According to an interview on "The Howard Stern Show", director Jon Favreau considered casting him as the titular character in "Iron Man" as the studio was initially hesitant to work with Robert Downey Jr., who had been considered for his role in "The Hitchhiker's Guide to the Galaxy". Rockwell eventually appeared in "Iron Man 2", released in 2010, as Tony Stark's rival weapons developer, Justin Hammer. He is said to have accepted the role without reading the script. He had never heard of the character before he was contacted about the role and was unaware that Hammer is an old man in the comic books.