CEREBRA

CEREBRA was a mind parasite developed as a weapon. It was capable of infecting written words, including a printing press to create them, and affecting people who read. It had no body and relied on possessing humans.

CEREBRA's core host would appear with wizened skin and milky eyes, CEREBRA appearing as a white mist when it left through their eyes, nose, and mouth; once abandoned, the host would regain their former appearance.

In the 22nd century, CEREBRA devastated Washington DC until the Seventh Doctor and Ace stopped it, afterwards confronting CEREBRA Commander, the core host, though CEREBRA didn't view the host as an individual. Having built a crude time machine crackling with red and purple electricity, CEREBRA wanted to spread its influence throughout human history, the Doctor considering it a despot.

It successfully escaped to Washington on 24 July 1814 where Ace pursued it, having infected a copy of Robinson Crusoe and some other books she was able to burn. The Doctor aided the invading British in tracking down the rest of CEREBRA, finally burning all of it with the White House. However, George Cockburn saved a melted 'C' typeset, obsessed with the power to change men's minds. (AUDIO: Washington Burns)