Limbo

Limbo was like a white Void. The Trickster and his Graske had access to Limbo, and could materialize and dematerialize in and out at will.

The Trickster had sent Sarah Jane Smith to Limbo when she was removed from time. Maria Jackson was also sent here. (SJA: Whatever Happened to Sarah Jane?) It's also possible that The Doctor was sent here when Donna Noble created an alternate timeline in which the Doctor was erased from history. (DW: Turn Left)