Dr. Victor Presper was going to be the main antagonist in the cancelled version of Fallout 3, Van Buren. He is a brilliant mad scientist who used to work for the NCR and has the goal of preserving the "master race" of pure humans, as opposed to mutants. To this end, Presper intends to use an orbital satellite called the B.O.M.B. -001 to launch nuclear weapons at parts of the Earth, as well as a virus engineered by a computer called the ULYSSES (not to be confused with the canon character). He would keep the humans that he had chosen to save inside the Boulder Dome until he deemed it safe for them to go out into the even more devastated than before world and start repopulating it, and it would have been up to the player to stop him, had the game ever been finished.

           Fallout Villains

China | Great War | Vault-Tec

Recurring Groups and Creatures
Super Mutants | Deathclaw | Enclave | Raiders | Khans

Fallout 1
The Master | Lieutenant | Morpheus | Gizmo

Fallout 2
Frank Horrigan

Fallout 3
John Henry Eden | Colonel Autumn | Mr. Burke | Stanislaus Braun | Roy Phillips | Allistair Tenpenny | Eulogy Jones | Talon Company | General Jingwei | Professor Calvert | Wernher | Ishmael Ashur | Aliens

Fallout: New Vegas
Caesar's Legion (Legate Lanius, Vulpes Inculta) | Benny | Mr. House | White Glove Society | Omertas | General Lee Oliver | Fiends | Tabitha | Father Elijah | Dean Domino | White Legs | Think-Tanks | Ulysses

Fallout 4
Conrad Kellogg | Shaun | Mayor McDonough | Arthur Maxson | The Institute | Gunners | The Forged | Eddie Winter | Marowski | Bobbi No-Nose | Lorenzo Cabot | Sinjin | Dr. Chambers | Triggermen

Fallout Tactics
Calculator | Simon Barnaky

Van Buren (Cancelled)
Victor Presper | Joshua Graham