Doctor Who: EVERY NuWho Villain And Monster Ranked Worst To Best
185. Sentient Oil
Appears in: The Pilot, The Doctor Falls.
There's wooing, there's stalking, and then there's shapeshifting fluid that takes the form of your mutual crush and follows you across the universe. They do say love knows no bounds, after all.
It's your typical Steven Moffat love story where girl (Bill Potts) meets girl with a star in her eye, the lovely but troubled Heather, who gets absorbed by a sentient puddle of oil that was left behind by an alien spacecraft. From there, Heather does her best T-1000 Terminator impression in pursuing Bill and provides some scares here and there, particularly the starry eye down the plughole.
The sweet pair eventually get their happily ever after, but this is all about the baddies, and it's a shame that the Doctor and Bill didn't encounter the aliens who use this particular engine oil for their ship. Oil that also talks creepily like Colony Sarff! Seriously, who would use such stuff?!