Most cliffhangers are immediate affairs. There's a twist in the plot. A close up of the Doctor's/companion's face. Cue musical sting. This one from 2007, however, is a great example of the rolling drama type of cliffhanger. At the end of the universe, it turns out that kindly old Professor Yana has a fobwatch that contains his true Time Lord consciousness. He opens it and is revealed to be the Master. Locking himself in the TARDIS, he regenerates and leaves the Doctor & Co abandoned, with no way out. As one of the most exciting cliffhangers of the new series, this has so much going for it. A shock twist, a return of a fan-favourite foe, and a regeneration all in a short space of time. Also, up to this point (and ever since, come to that) finales were only two parts long. This twist, though, made this apparently standalone episode into something bigger - the first instalment in an epic three-part finale featuring the Doctor's arch-enemy. In a nutshell, it is simply a masterclass (chortle) in how to do a Doctor Who cliffhanger.
