Space Leech
Space Leeches are green flying creatures with a crusty shell that attach themselves to people heads and suck the life out of them. They have six main appendices, two long frontal claws and two matching long limbs just behind for grabbing their prey, two shorter limbs can be found at their back end. Their fleshy mouth is a sucker-shaped funnel with razor sharp teeth and a central proboscis for a tongue that attach to peoples heads.
They are known to travel in space, but their level of technology remains unknown. When a spacecraft crashed in London on Earth April 2010 the Space Leeches swarmed from the wreck and attached themselves to the heads of Londoners sucking the life out of them. They were susceptible to a highly contagious virus manufactured by the Doctor from a cold virus carried by a young lad called Stephen. Detaching themselves from the virus-carrying people they were attracted by the Doctor’s biology and were last seen following the Doctor into his TARDIS.