2. Timey-Wimey
Ask anybody, fan or otherwise, what Doctor Who is about, and it's a fair bet they'll say "Time Travel". And they'd be right, obviously. But how many Who stories actually feature time travel as a central premise, beyond using it to get the characters to the location in the first place? Answer; not that many. On top of the Weeping Angels, the credibility of the Doctor-Lite story and Carey Mulligan's exploding popularity, Blink is also known for launching the phrase "Wibbly Wobbly, Timey Wimey." The nonsensical saying has become a mainstay of any New Who episode that needs to describe time paradoxes to a layman, but it can also be retroactively applied to older stories. Namely An Unearthly Child. By way of its then-novelty status, An Unearthly Child can be counted as one of the few Classic Who stories that is really about time travel, for two main reasons; Susan - the titular child who seems to have both full knowledge of the future (the episode correctly predicted British currency's move to the decimal system, in a lovely instance of life imitating art) and blithering ignorance of the present. Then there's the TARDIS, as previously said. Ian, Barbara, Susan and the Doctor spend virtually the entire episode talking about time travel, from the classroom to the Console Room, as they rhetorically set up the ensuing 50 years of adventure. Fast-forward 44 years, and Sally and Larry are having the same conversation, almost. The central plot-device of Blink is the "chinese puzzle" temporal conversation between the Doctor and Sally, via a pre-recorded DVD 'Easter Egg' where the Doctor has a transcript of everything she will say. Time Travel, as well as the Doctor and the TARDIS, is the third common element of Doctor Who that both episodes stop to actually utilise in their stories.