J

As spoken by the Tenth Doctor and the entity possessing Sky Silvestry, J was the tenth letter of the alphabet, following I and preceding K. (TV: Midnight)

Behind the scenes

 * According to The Dalek Dictionary, the letter J is "the forbidden letter" of the Dalek language: added to the beginning of any sentence or phrase, it adds an insulting meaning to it. For example, whereas "galkor" simply means "Follow me, I am your guide", "j'galkor" would come across as "Follow me, weaking! I am your guide".