3. Henry Knight
The Sherlock adaptation of Conan Doyle's The Hound of the Baskervilles is probably my favourite episode of the show. It's the one episode that is truly scary and makes you jump. Sherlock's character also gets examined far more than ever before as he begins to doubt his deductive powers and his eyes. The real star of the show though is troubled Henry Knight, played superbly by Russell Tovey, who acts as the anchor of the episode. It is his words ('they were the footsteps of a gigantic HOUND') that spark Sherlock's interest in the case and his meetings with his therapist. Also, the Hound in Dewer's Hollow showcase his descent into madness beautifully. However, it is Tovey's portrayal of Henry Knight that gets him on this list. He plays him excellently as a quivering, demented fool but he still manages to capture the real human centre of the character. It is a testament to his performance that we feel happy for the character after his ordeal is over.