G

As spoken by the Tenth Doctor and the entity possessing Sky Silvestry, G (Morse code: --. (TV: The Man Who Never Was)) was the seventh letter of the alphabet, following F and preceding H. (TV: Midnight)

The Ghost flying over New York City. (COMIC: Ghost Stories)

As the superhero known as the Ghost, Grant wore a suit with a big G on his chest. (TV: The Return of Doctor Mysterio)