"Robot of Sherwood" is the third episode of the eighth series of Doctor Who. It starred Peter Capaldi as The Twelfth Doctor, Jenna-Louise Coleman as companion Clara Oswald, and Tom Riley as Robin Hood.
Clara asks the Doctor if they can visit Sherwood Forest and meet Robin Hood, and despite the Doctor telling her that Robin Hood is a myth, he complies. When they land, they immediately meet Robin Hood, and the Doctor (and the audience) quickly spend most of the episode trying to figure out just who exactly Robin Hood is---because, of course, this being Doctor Who, a legendary figure has to be a robot, or a hologram, or a shape-shifting alien. While trying to figure this out, the Doctor also has to figure out why the Sheriff of Nottingham has robots working for him, and why he is stealing people's gold.
Compared to the last two episodes, this episode was much lighter, being a fun adventure story. Although there is some violence, it is less visceral, and is mostly of a swashbuckling nature. In some ways, this story resembles Season Six's "The Curse of the Black Spot"---an adventure story that provides a slight breather from a plot and themes of a complicated story arc. This story also does ensure us that the Twelfth Doctor will have a humorous side, as well as a serious side.