Mandragora Helix
From Multiversal Omnipedia
The Mandragora Helix was an otherdimensional energy being which used the Fourth Doctor's TARDIS to get to Renaissance-era Italy, where it possessed the members of the Cult of Demnos. Their leader, the astrologer Hieronymous, was the most altered, becoming nothing more than energy in the shape of a man. The Doctor eventually banished the entity, but warned that it would be back in a few hundred years.
Comments
It was due to return in the 1990s- apparently, it was defeated a second time.
