Just surfing around I found this on Google Images:
Turns out to be the creation of Anna of Life, Craftiness and Everything Else. And the little guy — whose name is Dale — is available for sale and custom order (like if you want him in a different color) at The House of Mouse on etsy.
No. Wait. It gets better. Anna does other Doctor Who characters as mice. Such as the Fifth Doctor:
And a Weeping Angel:
Oh, just go see all of them and die from the cute.
(If you stumble across a cool Doctor Who thing, feel free to email me with a link.)