1. Doctor Who - Regeneration
Well here it is, quite possibly the greatest plot device in the history of television. A single idea made more out of necessity than inspiration, which has resulted in one of the longest running shows of all time. As you probably know 2013 marks the fiftieth anniversary of Doctor Who and one of the biggest reasons for this success came about in only the fourth season of the show, when the lead actor and then only Doctor needed to vacate his role. William Hartnell was the first Doctor, he had battled the Daleks and the Cybermen and had laid the groundwork for what would follow, but his health was beginning to fail him and it was decided that he would leave. The show was very successful and despite the impending loss of its lead the BBC wanted it to continue, so it was decided that due to the Doctor being of alien origin, he would be able to renew his body. This meant that whilst remaining inherently the same person, the character could change his appearance and personality, thus allowing a new actor to come in and play the role differently from the last. So with the recommendation of Hartnell himself, the BBC hired Patrick Troughton to play the second doctor and history was made. Troughtons second doctor wad a considerable change from the first, gone was the grumpy old man and in his place was an eccentric kook. This transition set the precedent for the approach to regeneration, though it was undoubtedly still the same show the actor and his take on the character were so different that it felt new, so each new doctor represents a new start for the series. No matter how popular certain actors are- namely Tom Baker and David Tennant- the show will go on. The regeneration also creates a new jumping on point for the show, for example potential viewers who werent draw in by or didnt like the David Tennant era may have found Matt Smiths eleventh doctor more to their liking. This ability to restart the show helps keep Doctor Who alive, and with Peter Capaldis twelfth Doctor looming- its about to happen all over again.