re: Spinoff: Worse if they really existed: Vampires or Werewolves.

Vampires. Werewolves only transform for a few hours a month, and you could keep tabs on them. Don't need to kill them, just lock them up the day of the full moon, keep them in lockdown through the night, and they come back 28 days later.

Vampires though would be a constant threat. They'd abduct us, harvest us for our blood, and then kill us. They'd be far more organized than Werewolves would be since their lives depend on it.