Malus

The Malus was a creature re-engineered by the Hakolians for their invasions.

It was sent to Earth in the 17th century, where it laid in suspended animation until 1643, when it was awoken by the battle at Little Hodcombe and began feeding on the psychic energy generated by the negative emotions. The Malus went dormant again once the violence subsided.

In 1984, the Malus was discovered by Andrew Verney and Sir George Hutchinson. The creature took control of Hutchinson and tried to use him to generate more psychic energy upon which to feed.

The Malus was defeated when the Doctor used his TARDIS to block its' feeding, and when Hutchinson was killed, it destroyed itself and the church it had based itself in. (DW: The Awakening)

Despite being a villian the Doctor shows great pity for the Malus claiming that killing is the only thing it knows how to do, suggesting it was a benevolent creature the Hakolians re-engineered it in to a killing machine.