Vault 144

Vault 144 is mentioned in the quest "Give me Libery and/or Death" in the questline Horsemen of the post-Apocalypse part 2 in Fallout shelter.

The Vault
The Vault is obsessed with Death after either a misspelling, but more likely intentionally by VaultTec where every spelling in the vault manual of Death is spelled with a Capital D.

They are portrayed in the Game as waiting for death, and about quotas of Death, to cause the arrival of Death