Doctor Who: EVERY NuWho Villain And Monster Ranked Worst To Best

Appears in: The Snowmen, The Bells of Saint John, The Name of the Doctor.

It's a tale as old as time: a sentient parasite in snowman form meets miserable young sod. Fifty years later, they're still a match made in hell - a giant, sinister snow globe with the velvety tones of Ian McKellen feeding off the darkest dreams of the permanent resting bitch face that is Dr Walter Simeon (Richard E. Grant).

At this point, the Great Intelligence and Simeon have cultivated quite the symbiotic relationship, in that they've become one and the same. This truly manifests when "the dream outlives the dreamer" and takes control of Simeon's body (honestly, you and your memory worms, Doctor!), but only momentarily due to a family crying over a dying Victorian version of Clara.

However, the Great Intelligence did make good on their promise to "never die", and used Simeon's face for its official look, one that we see briefly in The Bells of Saint John and via the Whisper Men in The Name of the Doctor.

Given the heavyweight acting calibre of McKellen and Grant, they were disappointingly underused in The Snowmen and, to use the mirroring analogy from the Great Intelligence, this is reflected overall in its other two appearances. To think, you'd have expected an awesomely epic aftermath when Simeon steps into the Doctor's time stream. Instead, we get a bit of a light show and some ropey CGI.

We'll chalk this one up to Steven Moffat's "miserable" time writing Series 7.