Process

The Process was a parasitic life form of an unknown species which resembled a slimy worm or leech but with lamprey-like mouths at each end. It possessed clawed fins and red-brown skin which turned grey with age. It moved by cartwheeling itself footmouth over footmouth, leaving a slime trail behind. The Seventh Doctor speculated that it was a datavore (a creature which consumed information for food). In the Book of Future Legends, it was known as the Amphisbaena.

The creature attempted to get inside the TARDIS, which warned the Doctor and Ace of the danger it was in. They quickly returned to the ship, which the creature then began leeching of power. Before the Doctor could find a way to deal with it, the TARDIS collided with the Time Scaphe, which activated its Banshee Circuits and caused it to reconfigure itself into a multi-dimensional city. The creature, its size increased a hundredfold and now calling itself the Process, enslaved the Time Scaphe crew and made itself ruler of the city. When Ace disrupted the Process' timeline, it sought to create a new world, eventually deciding to summon the egg from which it had hatched so it could supervise its own birth. However, Vael, intending to kill the Doctor, instead accidentally turned the full force of his mind against the egg, incinerating it and thus preventing the Process and its timeline from coming into being. (NA: Cat's Cradle: Time's Crucible)