Fallout endings

Returned to normal Vault life
Prerequisites: Refuse to or fail trying to find the water chip.

Military Base
Prerequisites: Destroy the Military Base.

Cathedral
Prerequisites: Destroy the Cathedral.

Master's victory
Prerequisites: Join the Unity (reveal the location of Vault 13 to the Lieutenant or the Master), or let 500 days pass with the Master still alive alive (or 13 years regardless).

Ending 1
Prerequisites: Destroy the Military Base before taking the Cathedral.


 * The Vault Dweller's memoirs establish this ending as canon.

Ending 2
Prerequisites: Destroy the Cathedral before the Mariposa Military Base.

NOTE: although the narrative plays out to be the other way around, the game is bugged to obtaining the opposite ending.

Water pump maintained
Prerequisites: Take the chip, fix the pump.


 * This ending is partially canon, as mentioned by some ghouls like Lenny in Gecko.

Dehydration
Prerequisites: Take the water chip, but don't fix the pump.

Mutant attack
Prerequisites: Enter Necropolis after 110 days have passed, or kill all the super mutants at the watershed and enter after 30 days have passed.


 * The Vault Dweller's memoirs and Fallout 2 establish this ending as canon.

Gain control of Boneyard
Prerequisites: Complete the Find Children spy in the Followers quest and train the Followers in use of firearms.


 * Fallout: New Vegas establishes this ending as canon, despite the fact that it is impossible to obtain due to Heather's absence.

Killed by mutants
Prerequisites: Either the Master is still alive after 90 days, or the player fails to find the Children of the Cathedral spy within the followers.

New California Republic
Prerequisites: Aradesh and Tandi are alive.


 * Fallout 2 and New Vegas establish this ending as canon.

Aradesh grieves Tandi
Prerequisites: Tandi is dead or not rescued, Aradesh is alive.

Tandi takes over
Prerequisites: Aradesh is dead, but not Tandi.

Destroyed by raiders
Prerequisites: Aradesh is dead, and Tandi is either dead or still being held by the Khans.

Razed by mutants
Prerequisites: The Master is still alive after 230 days have passed. Takes precedence over the other endings.

Junktown
In the original write-up of Junktown, the "ending sequence" was reversed from its final incarnation. See the alternate endings for the original versions, which were changed because the marketing department decided at the last minute that the game had to "reward good and punish bad".

Killian takes control
Prerequisites: Gizmo is dead, Killian is alive.


 * Fallout: New Vegas and J.E. Sawyer's Fallout Role-Playing Game establishes this ending as canon

Alternate version
[With the background picture being a gallows behind Killian with shadows of dead men hanging from it.]

Gizmo takes control
Prerequisites: Gizmo is alive.

Alternate version
[With the background picture showing Junktown as a Reno-like casino with electricity and clean streets free of any drug dealers or riff-raff who might endanger Gizmo's operations.]

Destroyed by mutants
Prerequisites: The Master is still alive after 210 days.

Drive mutants away
Prerequisites: Rhombus is alive.


 * Fallout 2, and post-Fallout 3, establish this ending as canon

Dictatorship
Prerequisites: Rhombus is dead.

Traitor
Prerequisites: Kedrick is alive, or the Master is alive for 170 days.

Prosperous trade center
Prerequisites: You must complete the quest find the missing caravans, don't fulfill any of Decker's quests, complete the quest Report Iguana Bob to the Hub police, and be friendly with Harold.


 * Fallout 2, Fallout 3 and New Vegas confirm that this ending is canon, despite the fact that it is impossible to obtain due to the Report Iguana Bob to the Hub police quest being absent from the game.

Abandoned
Prerequisites: Do not complete the quest to find the missing caravans, complete at least one quest from Decker, or the Master is alive after 140 days.

Destroyed as a fighting force
Prerequisites: Kill Garl and at least eight more raiders, or kill at least thirteen raiders.


 * Fallout 2 and New Vegas establish this ending as canon (although a single Khan survivor, Darion, is found from Vault 15 in Fallout 2, where he is quite influental).

Regroup and terrorize
Prerequisites: Enter the raider camp but don't kill enough raiders for the previous ending.

Scourge that lasts for years
Prerequisites: Do not enter the main camp of the Khans.

Kill the Overseer
Prerequisites: To do this you must have the blood mess trait. You can get this in character creation or by using the perk Mutate!. Then by the end of the game you must either have low karma, or initiate combat after your talk with Jacoren

The Overseer lives
Prerequisites: Don't kill Jacoren.