Griffelian V

 was a planet known to K9 Mark III. The inhabitants of the planet were amorphous masses of protoplasm. When Sarah Jane Smith stated, "Tell me something I don't know", to her robot companion, K9 took the phrase literally and began to detail the obscure planet to her. (COMIC: City of Devils)

Behind the scenes
In the Audio Visuals Subterfuge, Griffelian V is a Conglomerate training planet. The Doctor, Ria, and Truman Crouch meet with Cuthbert on this planet.