White void

The White Void was a place where the White Robots existed.

History
The Doctor's TARDIS arrived in the White Void after the Second Doctor flicked an emergency switch in order to escape a volcanic eruption.

Zoe and Jamie found the TARDIS scanner showing them the void, and then images of their homes, making them believe they had returned. The Doctor believed, correctly, that some force outside meant to use these illusions to tempt Jamie and Zoe to leave the safety of the TARDIS. Zoe did leave, with Jamie following after to rescue her. In the Void, the exterior of the TARDIS itself turned white.

Two forces existed in the Void. One were the White Robots, who captured the Doctor's companions. The second was the creator of the illusions, who mentally vied with the Doctor's will in the TARDIS console room. The force took over Zoe and Jamie, turning their clothes white. The Doctor broke the force's hold and returned his companions to the TARDIS. (DW: The Mind Robber)

Behind the scenes

 * The White Void presumably has some connection with the Land of Fiction which they would encounter subsequently, if not with the Master of the Land.
 * Another mostly-white void which had zero co-ordinates existed between N-Space and E-Space. It was known to the Tharils as the Gateway. (DW: Warriors' Gate)
 * Adam Smith may have been trapped in this void. (TW: Adam)