Frankenstein, Doctor Nemesis, Domino, Elixir, Manuel Enduque, E. A., Fantomex, Firestar, Forget Me Not, Frenzy, Emma Frost, Gambit, Goldballs, Havok, Hellion, Hepzibah, Hope, Husk, Iceman (Young), Joseph, Juggernaut, Karasu, Karma, Ziggy Karst, Krakoa, Kymera, Lady Mastermind, Legion, Lifeguard, Loa, Lockheed, Logan, Longshot, Lucid, M, Maggott, Magneto, Marrow, Marvel Girl (Young), Mimic, Mystique, Namor, Northstar, Omertà, Onyxx, Petra, Phoenix, "Phoenix", Polaris, Prodigy, Professor X, "Professor X", Psylocke, Dr. Mutants are often hated and feared by other humans because they are different from themselves.
Before executing the X-Men, Factor Three revealed that they intended to initiate World War III by attacking both the United States and Russia, sparking a nuclear exchange between the two.
Their next adventure found them defending Washington D. They first clashed with the X-Men when the Brotherhood took over the nation of Santo Marco During this period, the Professor briefly left Cyclops in charge of the school while attempting to stop the alien Lucifer from conquering the world.
This attempt was foiled thanks to the assistance of the X-Men and the Avengers, beginning the two groups' long-standing association.
Annie Ghazikhanian (former nurse), Harmony Young, Stevie Hunter (former staff), Illuminati (defunct), Kyle Jinadu, Kate Kildare (public relations), Leech, Dr. Xavier vowed to protect the world from the threat of evil mutants and endeavored to foster peaceful coexistence between humans and mutants.
Moira Mac Taggert (deceased), Mighty Avengers (Initiative) (defunct), Muir Island X-Men (defunct), New Avengers (defunct), New X-Men (defunct), Nocturne, Pulse (honorary member), Red Lotus (honorary member), Runaways, Sashia, Secret Avengers (defunct), Sentinel Squad O*N*E (defunct), Candy Southern (deceased), Spider-Man, Spider-Woman, Starjammers, S. Working with Moira Mac Taggart, he eventually decided to start a school for mutants, training them to be what would eventually become his first "X-Men".
Factor Three struck again when the Professor attempted to cure his step-brother of being the Juggernaut.