Hindmost
From Tardis Wiki, the free Doctor Who reference
In an alternate universe, Hindmost was the most remote significant piece of baryonic matter known to the Time Lords; it was so far from Gallifrey that a TARDIS would have to be specifically re-engineered to make the journey. Hindmost was described as being a planetoid barely big enough for a man to stand on. (PDA: The Infinity Doctors)
