(K)nox: The Rob Knox Story is a British documentary about the life and murder of Harry Potter actor Rob Knox, who was killed in 2008. The film is directed by Aaron Truss and features interviews with Knox's friends, family, and colleagues in the film and TV industry. The film also highlights the knife crime crisis in the UK since 2008, after Knox's death. The title of the documentary is a reference not only to Rob Knox, but the Nox charm used in Harry Potter that extinguishes the light at the end of a wand.