The Beast (The Taint)

The Beast was the name given to a species of flying extra-dimensional parasites. They were normally invisible to most species. They would travel from planet to planet, feeding on the life force of the native populations without harming them, and departing after having their fill.

Centuries ago, they traveled to Benelisa and fed on the natives, but since their population was so low, the Benelisans were unintentionally wiped out. Before dying, they sent out Azoth to locate and destroy the Beast.

In the 20th century, the Beast came to Earth and fed on the Humans there. Azoth attempted to eradicate the Beast, but was prevented from doing so by the Doctor.

By 2134, the Beast had departed Earth. (EDA: The Taint)