Vault-Tec Corporation, otherwise known as Vault-Tec and sometimes called Vault-Tec Industries, is a fictional defense megacorporation from the post-apocalyptic Fallout franchise. Throughout the United States, Vault-Tec created government-funded vaults, large fallout shelters that would serve to shelter civilians and allow for the continuation of human life in the threat of a nuclear attack. Within most of these Overseer-governed vaults, Vault-Tec carried out human experiments on its residents without their consent or knowledge, ranging from being mostly harmless to disturbing and inhumane.

Vault Boy is the mascot of the Fallout media franchise. Created by staff at Interplay Entertainment, the original owners of the Fallout intellectual property, Vault Boy was introduced in 1997's Fallout as an advertising character representing Vault-Tec, a fictional megacorporation that built a series of specialized fallout shelters throughout the United States prior to the nuclear holocaust that sets up the world state of the Fallout universe. Within the video game series, Vault Boy serves as a representation of the player character's statistical information within user interface (UI) menus, and is a recurring element in Vault-Tec products found throughout the fictional Fallout universe. In the 2024 Fallout television series, Vault Boy is depicted as having been portrayed in Vault-Tec advertisements by actor Cooper Howard.