Shadow Dimensions

The Shadow Dimensions was a realm which Jack Harkness described as being devoid of anything but the sorrow and guilt of the lost and the breeding ground of creatures that drain emotional energy. (AUDIO: The Sin Eaters)

The Doctor banished Fenric to the Shadows Dimensions in a flask during their battle in the 3rd century at the conclusion of a chess game. (TV: The Curse of Fenric) According to the ancient Arabian legend of their encounter, the flask contained the "Seven Shadows". Like Fenric himself, the Shadows were a remnant of "the time before Time". (PROSE: The Curse of Fenric)

The Mandarin was unimpeded in reaching the location to challenge Fenric to a game. Looking at the grey void and its shifting patterns, he described it as unimaginative, a non-world, and "a dimension of shadows and half-lives." (PROSE: Games)

The Demon described his home as being "a tiny backwater in a shadow dimension ... bearing practically no resemblance to this physical universe." While the Shadow Dimensions were inside the flask, they may also have existed outside the universe, where the Demon was from. (AUDIO: Sepulchre)