Joseph Francis Mazzello III is an American actor. He began his career as a child actor and played Tim Murphy in Jurassic Park and Roarke Hartman in The River Wild. As an adult, Mazzello is best known for his portrayal of real-life figures Eugene Sledge in the HBO miniseries The Pacific, Dustin Moskovitz in The Social Network, and John Deacon in the biopic Bohemian Rhapsody.