Best Episode: The Invasion - The original Cyberman invasion down the steps of St Paul's Cathedral. Worst Episode: The Dominators - Dull. Just utterly dull. The Doctor that proved you could continue the show without the original leading man; if Patrick Troughton had not made the impact he did, the show might have faded way into failure and obscurity. Thankfully the Second Doctor was a terrific success. He not only brought something fresh with his playfulness and ability to disarm his enemy with his 'apparent' buffoonery, he also brought out a Doctor that audiences could truly engage with. Hartnell wasn't un-relatable, but he was the grandfather Doctor; he could be caring and wise but he could also be arrogant and aloof. Troughton's Doctor was the first Doctor who seemed to genuinely care deeply for his companions and who appeared to enjoy his experiences travelling the galaxy. There is so much of the Second Doctor's character in every subsequent Doctor - particularly Matt Smith's - that ensures his Doctor endures even today. Despite being more heavily affected than his predecessor by the BBC cull of the 1970s, some of those stories that remain are absolute classics. If Hartnell was the king of historical episodes, then Troughton was the king of monsters and in his episodes Doctor Who delivered some of the best scares of all time.