Hardboiled Android
Vault Fossil
But the same thing applies to any monsters they could potentially create?
How do you train them to kill only surface dwellers and ignore your people?
Plus once they wipe out everyone, then the surface is now filled with bloodthirsty creatures.
Do you create another mutant to get rid of them?
If only Vault Tec had something capable of destroing post-war civilizations that could be easily controlled from a safe place (like a Vault).
I mean it's not even like Gulpers are some super-death engineered killing-machine like Wannamingoes or Deathclaws, gulpers are just an animal basically. It would be like Vault Tec releasing angry gorillas to exterminate surface dwellers.