A Letter from the Doctor (series)
A Letter from the Doctor were short narratives, written as if by the Doctor himself.
The first "Letter" appeared in early issues of Doctor Who Magazine (including the very first) and occasionally in special anniversary issues celebrating milestones in the publication's history. More recently, in Annual-style publications such as Doctor Who Storybook 2008. This letter was actually written by Russell T Davies. In the Doctor Who Storybook 2009, the letter was written by newly appointed showrunner Steven Moffat.
The letter in the Doctor Who Storybook 2010 -- written once again by Davies -- is different in format than the others, taking on the appearance of a garbled transmission from the Doctor, apparently going back in time and including snippets of dialogue from various Tenth Doctor TV episodes going back to the incarnation's very first words. Because of this format, it's believed the first words of the letter may well be the last words of the Tenth Doctor.