Caution: spoilers ahead for Doctor Who season 15, episode 3, "The Well."

the Doctor's regenerations later, and the results proved just as terrifying.

"The Well" revealed more about the monster than "Midnight" ever did. For one thing, what Doctor Who's Midnight monster actually looks like. Nevertheless, the villain and its home planet remain wrapped in a shroud of mystery, and while this curious theory can plug a big gap in Doctor Who's Midnight lore, it makes "Midnight" and "The Well" far more chilling as a consequence.

Doctor Who Season 15 Implies How The Planet Midnight Got Its Name

Was Midnight Named After The Monster's Behavior?

Doctor Who season 4 never explicitly explained why the planet in question was called Midnight. One might have assumed the name was connected to the planet's glittering, jewel-encrusted surface, but Doctor Who season 15's "The Well" offered an alternative explanation. As Ncuti Gatwa's Fifteenth Doctor began formulating a plan against the killer creature, he and Belinda figured out victims would be slaughtered as soon as they stood directly behind the host - the 12 o'clock position on a clock face.

It would make more sense if Midnight was named because of how the monster hunts.

Fifteen verbally noted how this corresponded to the planet's name, Midnight, but went no further in his assumptions on the matter. And yet, Doctor Who's Midnight monster killing prey when they reach the 12 o'clock position cannot be a coincidence.

Unless it has a particularly good sense of humor, it seems highly unlikely that the Midnight monster chooses to attack victims when they stand at 12 o'clock as a clever nod to the name of its home planet. Instead, it would make more sense if Midnight was named because of how the monster hunts. Long before the Tenth Doctor landed his TARDIS there, perhaps another band of explorers set foot on the as-yet-unnamed diamond planet. They faced the monster, and realized anyone behind its host would die, but maybe their story survived, and the planet became known as Midnight to warn future visitors of where not to stand.

How Midnight Got Its Name May Explain Why There's Only One Monster

The Monsters May Have Wiped Themselves Out

Working on the assumption that the Midnight monster has been killing those who sneak behind its host's rear for, potentially, millions of years, and that this is how the planet Midnight got its name, it becomes possible that there was originally more than one of them. Because of the rules surrounding the monster's attacks, however, the species would have whittled itself away over time, killing each other until only a single specimen remained, just like the occupants of Aliss' mining base.

This lone survivor, of course, would be the creature the Doctor meets in "Midnight" and "The Well," now the last of its kind and coming off the back of countless eons spent alone.

It's even possible that, back when there was more than one of its kind, these life forms were largely benevolent. Being cursed to watch its entire race being obliterated, combined with so much time spent alone dwelling on its misfortune, could explain why the monster became so vile and twisted. It's a victim of its own biology, which would for why the villain apparently has no motivation beyond inciting fear in others and escaping from Midnight.

If This Really Is The Monster's Backstory, Doctor Who's Entire Universe Is In Trouble

Can Midnight's Monster Even Be Killed?

In the final moments of "The Well," Doctor Who confirmed that the monster ultimately stowed away from Midnight and entered the wider universe to wreak havoc and, most likely, terrify the Doctor once again in an adventure. If the theory about Midnight being named after the creature and the species hunting itself into near-extinction is true, however, the Doctor may struggle to fight back during their next battle.

A creature that old and twisted has no obvious weaknesses the Doctor can exploit. A mirror can repel it temporarily, but as "The Well" proves, it jumps right into a new host and the cycle begins again. According to the theory, the only thing known to kill a Midnight monster is another Midnight monster, but with only one left in the universe, this shadowy entity might be destined to roam from planet to planet for the rest of time in Doctor Who. Unfortunately for the universe, the Doctor appears powerless to do anything about that.