21. The Lodger
'What would the Doctor be like in the everyday world?' is the question that this delightfully lighthearted episode poses. In fact, so successful is this episode that the basic premise has been redone several times since - Closing Time, The Power of Three, The Caretaker... but this remains the original and the best. A story perfectly suited to the quirky, off-kilter Eleventh Doctor, this is probably Doctor Who's most successful 'comedy episode'. Matt Smith and James Corden make for a great double-act and Craig and Sophie's romance is rather sweetly done. It might not be packed with drama and scares but sometimes it's good to have a Doctor Who played for laughs over everything else.