C
From Tardis Wiki, the free Doctor Who reference
As spoken by the Fourth Doctor, C was the third letter of the alphabet, following B and preceeding D. (TV: The Masque of Mandragora)
As early as his sixth incarnation, the Doctor kept a "C chest" aboard his TARDIS, named for containing a cache of items marked by the letter C. (TV: The Unicorn and the Wasp)
