Billy Crudup plays one of the band members Russell, the member of the band William most gets to know somewhat due to Russell's involvement with a groupie who calls herself Penny Lane (Kate Hudson). Crudup technically plays Russell as the most down to earth member of the band, although that really is not saying a lot as one never speaks, another seems completely out of it, and the lead singer has an ego that outweighs his talent. Crudup deserves credit though as he is the only one of the actors playing members of the band who really gets much of anything out of his role, Jason Lee plays his role a little too broadly throughout the film and is not able to make much of an impression.
The whole character of Russell Hammond is a mix of things as he often is changing attitudes, and personal style often. This is rather fitting though because of the nature of the rock star life where there seems to be a non-stop energy and mind altering substances are plentiful. Through most of the scenes where he is interacting with William the journalist, or his fans whether it be a somewhat somber affair, or a very non sober affair Crudup brings an effective low key charisma with his performance. He brings that rock star quality into the role of Russell and makes it very believable why so many would be enamored with him, and why the lead singer of the band would find him to be such a threat.
One of the aspects of the film is basically revealing the problematic nature of the rockers life styles. Crudup is equally good in the bring down scenes because he loses the charm in the right sort of way. Crudup does not portray it as Russell stops putting on a show or anything like that, instead he just very realistically reveals the negative qualities as something always there as well that can come out almost as easily as the charm. In this moments Crudup is quite good by just being an average jerk frankly. When the nature of Russell really does come out, Crudup does not make it anything notable but rather the average off putting tendencies of a human being who gets more than he really deserves.
Out of the supporting actors in the film my favorite was easily Philip Seymour Hoffman in his short appearances as a rock critiic who hates egos while seeming to have a rather large one himself. Hoffman in his few short scenes left a stronger impression on me overall, but Billy Crudup does give a pretty strong performance as well and is easily the best performance in the many scenes featuring the antics of the band. His character is very important to the film as he basically sets up the many steps the plot of the film takes. Crudup fulfills his part nicely and brings to life properly the mix impressive and problematic elements found in the personality of a rock star.