The Daleks. A uniquely British science fiction "baddy". Nothing more than a dustbin armed with a sink-plunger and an egg whisk. Evil killing machines that can't be stopped by the best that human arsenals have to offer - other than a flight of stairs.
Yet, despite this, the Daleks are scary. I think it is easy to be scared and frightened of the Daleks because, well, they are so different from us. Metallic monsters, without even the slightest sign of any emotion other than to 'Exterminate'; it is very easy to hate or be frightened of things or people who are different.
You can tell Terry Nation, the creator of the Daleks was a humour writer - he wrote for Tony Hancock - because there is a satirical irony even in their first TV appearance behind the notion of racial purity and genetic mutation. The Daleks are a race - rather like the Nazis - obessed with genetic purity, but as a result of a thousand year neutron war have become malformed and infirm, only able to live inside their mobile iron-lungs. Their erstwhile enemys, the Thals, however are tall, blond, blue-eyed Aryans. And yet are considered the mutants! The [mad] scientists tampers with the genetic make up of the Kaled race to find their 'final mutational form'; by tampering with the resulting creature's genetics, the pursuit of racial purity leads to absolute racial corruption. That the Daleks represent the idea of eugenics is what is at the heart of what makes them so scary: when you strip away the outer casing what is inside is a little seething mass of brain, tentacles and very little else, which is considered to be the final, purest form of the Kaled people, the 'supreme being in the galaxy.' That the Daleks were once 'like us' but were bred to be a seething mass of tentacles and indoctrinated to hate, having all other emotions purged. And that's scary because we too are capable of similar indoctrination, political or religious.
Because they are so very differant from us makes that them more effective as the villain. Despite their ludicrous appearance - a pepperpot and sink plunger - they are scary. Especially when they are silent, unmoving, unspeaking. Brooding. Watching. Just as it is a human instinct to be attracted to our own phyiscal form, to physical beauty, health so we are repelled, perhaps, by the differant. This is called 'dysmorphobia' - the central idea of most monsters in fiction: Richard III, Frankenstein's monster, the Phantom of the Opera. Thankfully, as a society we have moved away from seeing "that beautiful as always being good". But the Daleks tap into that: they have no normal (for humans) points of reference. No mouth. No eyes. All the anthropomorphic queues we look for are entirely absent. We just do not know what they are thinking.
Rather like the Phantom of the Opera or Darth Vader, we never actually see a Dalek (or seldomly so). We only ever see the mask - the outer casing. We never see the 'true' self of a Dalek. And that's part of their hidden power and why they work so well as 'baddies'. It's up to the viewer to picture the seething mass wihin. The Daleks, perhaps, are therefore more effective 'off screen' than on it - they are always hidden, kept veiled. We only see what they want us to see. They are fundamentally dishonest.
But ultimately, I think the Daleks are scary because they play on our fears - as do all the best villains. When Terry Nation created them back in 1963, the racial theories and exterminations of the Nazis would have been fresh in the mind. The Daleks just aren't alien monsters. They are a reflection of ourselves, what we are capable of. They are a warning from history and warning from the future. Whenever we see a mass rally of identically drilled soldiers or political followers, you're seeing human beings acting like Daleks. When we see politicians or church leaders attacking the 'other' - those who do not conform - you are hearing the voice of the Daleks. Sexism, Ageism, Homophobia are all Dalek values. The belief that only the 'superior being' deserve to survive and that the weak, the poor, the hungry and powerless are a burden is a Dalek belief.
In the episode 'Asylum of the Daleks' Oswin had been converted into a Dalek. And she didn't realise it. And she probably didn't have a choice either.
And this is why they are frightening. Because we are the Daleks.
Unlike the Daleks we have a choice. We have a choice whether or not to be a Dalek. The decision we have to make is whether we want to live our lives according to the values of the Daleks or the values of a cloud of witnesses attesting to the essential goodness of humanity: values exemplified by the Buddha, by Jesus of Nazareth, of inclusive welcome and radical hospitality in our hearts, in our homes, in our lives. Or whether we wish to be exclusivist, and uphold the values of a Dalek.