The Great Intelligence; also seen before in Classic Who.
Notice how it always takes a different form. In Classic Who it was ”a mass of tentacles and mouths” but took over other life forms too. In The Snowmen it’s snow and in the episode The Bells of Saint John it’s Wi-Fi (with an actual proper face this time). Also notice how in the last two episodes it took over kids, first Walter Simeon, who was just a little boy when the snow started talking to him. And second Miss Kizlet, who still had the mind of a little girl when the Great Intelligence let her go.
For more on The Great Intelligence, check out this post on the BBC Doctor Who site and watch the Second Doctor stories The Abominable Snowmen and The Web of Fear.
(Source: thesarahjanesmith)
Find out more about the Doctor’s old enemy…The Snowmen saw the return of the Great Intelligence, the malevolent force that threatened to destroy humanity through the sinister Doctor Simeon. It was the first adventure in over forty years to feature the Intelligence, so what’s the story behind this terrifying and mysterious foe?
The Great Intelligence first appeared The Abominable Snowmen, a 1967 story set in a remote Himalayan monastery. It returned the following year in The Web of Fear where the Doctor was able to foil its attack focussed on the London Underground and the 2012 Christmas Special saw the Time Lord facing his old enemy in Victorian England.
We’ve received lots of questions about the Intelligence’s previous appearances and so we’re delighted to roll out our Great Intelligence Collection. All three of their adventures are included and the collection comprises clips, information about the stories, galleries (including a behind-the-scenes look at their debut), Fourth Dimensions and much more…
The new pages include:

The Abominable Snowmen: Travel to the Himalayas for the Intelligence’s first adventure.

The Web of Fear: The Intelligence invades the London Underground
The Snowmen: The Great Intelligence returns in this creepy Christmas special.
The Second Doctor: Meet the first Doctor who encountered the Intelligence…
(Source: doctorwhogifs, via superdupertimemachine)