7. Robot
Tom Baker is so synonymous with Doctor Who that you forget he had to start off on the show somewhere. He did so in 1974, with an Earth-based story with The Doctor's friends at UNIT. They fight a big robot (which is a man in an awful costume) with the usual guns and even a tank, and anyone who has seen that scene will know the tank is not that impressive. Baker gives us a performance filled with humour, with little signs of the barking delivery we would see in later seasons. There's smiles, wit and even jelly babies. A ruthless side is shown with the finishing of the robot but his delivery is still rather light-hearted. The costume-changing scene was hilarious and one of the memorable scenes of the Fourth Doctor era. The episode is fun and I am sure many still laugh at the special effects on show. You just don't take the four episodes seriously, despite the Science Reform Society's best efforts as villains. As introductions go, it wasn't the strongest for the perennial favourite of the Doctors. https://www.youtube.com/watch?v=K3CWXqUqPFA