Morlog

Morlog is a mysterious entity that inhabits Earth in the year 2020, with the main goal of piercing the Doctor's mind, controlling him and making him part of his larger plan for universal conquest.

Biography
Morlog was created by a black hole that went inside itself and expunged purely negative energy, which eventually became sentient and manifested into the dark lord himself. At some point, he became stranded on Earth and was able to manifest a false reality in the form of a house existing within a park. The Doctor, having recently regenerated, landed the TARDIS in the middle of a park and was transported to the false reality house. After teasing the Doctor for a time, Morlog finally lured him into a small room and attempted to perform the mind penetration. The Doctor used his sonic penny whistle to reverse the effects and tear at Morlog's own mind, however, banishing him in between dimensions. The false reality house disappeared shortly afterwards, but not before the Doctor stole an outfit from it. It is unknown if Morlog survived, although a faint voice was heard saying his name as the Doctor left the area he was teleported back to.