Avengers, Assemble! is the twelfth episode in series four, and is really really good because it has a lot of things in it. It is one of the rare episodes to feature everyone in the known universe, with the exception of Griffith Stantsfield who was ill from the flu and had to be replaced with a CGI double. It is also well known for being the nuwho debut of Davros, portrayed by Julian "Rose Is Unemployed But Can Still Afford Hair" Bleach. It stars Richard Hammond as the Doctor, and Catherine Tate, Freema Agyeman, Billie Piper, John Barrowman, and Elisabeth Sladen as his companions, though only big mouth actually hangs out with him.