Eidolon

The  was a being from the time before recorded time, who lived in Ultima Thule. It was banished from N-Space by the Great Old Ones into another dimension out of fear of its power. After contacting several life forms from N-Space and attempting to lure them to its own dimension in the hope of escape, it finally succeeded in bringing the Sixth Doctor, Crystal, Jason and Karl to its home. After forcing them to relive their fears, it revealed itself to the travellers and informed them of its plans. However, the Doctor managed to trick it into entering the TARDIS after he had preset its coordinates, sending it to Gallifrey to be contained by the Time Lords. (AUDIO: Beyond the Ultimate Adventure)