Vault 77 is one of the Vault series of fallout shelters developed by Vault-Tec. It was featured in a promotional, crossover comic strip entitled One Man, and a Crate of Puppets, released to promote Fallout 3.
Vault 77 was sealed with only one person inside on October 23, 2077. This inidividual, later referred to as "Puppet Man", initially believed that this was a mistake and pleaded for the "other fucking people" to be let in. With his pleas unheard and unanswered, the years of solitude that followed took a toll on his mental condition.
On February 4, 2079, Puppet Man found a crate of puppets and immediately began playing with them. He quickly lost himself in his puppet games, and by March 30, he started to believe that the Vault Boy puppet was talking to him. That night, he tore apart the king puppet and then accused the Vault Boy puppet of the murder. The Vault Boy puppet responded that it was actually Puppet Man himself who "murdered" the king puppet, prompting the two to escape in fear for what the dog puppet might do. Puppet Man left Vault 77 soon thereafter, leaving the location uninhabited.
In 2277, a lone Vault 77 jumpsuit and a holotape can be found in Paradise Falls. The audio recording on the holotape states that the jumpsuit "freaks the boys out" because of a story about a "stranger with no name" from a while back, also fearing that if the jumpsuit is his, he might come back for it.