How important are famous actors to the success of a film or movie?

I'd say famous actors do play a significant role in a film's success, but it's not everything. Big names can attract initial attention and box office sales, which means studios are more willing to invest in marketing. For example, when "The Pursuit of Happyness" came out, Will Smith's star power definitely helped draw crowds in Shanghai cinemas. That said, the film's lasting impact came from its powerful story - people remember it years later because of the emotional connection, not just the actor. So while famous faces help with visibility, the real success depends on whether the story resonates with audiences.