The Master

Background

The Master used to be a man named Richard Moreau who was a resident of Vault 8. His occupation within the Vault was a doctor, but ironically he was kicked out of the Vault in 2092 for murder. With nowhere to call home, he changed his last name to Grey and made the decision to head south where he ended up in the trader city called the Hub. During his time there he formed a team with Harold, who was a well known businessman in the city. The partnership was formed as a result of an increasing amount of vicious attacks on Harold's caravan by mutated creatures. The two friends along with a team of scientists took it upon themselves to investigate and find out where the creatures were coming from. 
 

By chance, they happened on Mariposa Military Base which was the site of many Force Evolutionary Virus experiments by the United States government. When they entered the base, the team came under attack by defense units and messed up creatures that were transformed by the F.E.V. Harold managed to get away without being massacred, but Richard wasn't so lucky. A robotic arm seized hold of him and dumped him into a F.E.V. vat where he floated there for nearly a month. The severe exposure to the contaminant caused him to mutate into a horrific blob of mass that was capable of consuming anyone that came near the base. 
 
Richard Grey, now dubbed "The Master", became mad with power. He came up with the idea to transform every human in the Wasteland into Super Mutants, thus removing racial differences and creating a world that was better adapted to survival on the now-desecrated planet. Any human that came near the base was either consumed by The Master or was dipped into a vat.
 
At the end of the first Fallout game, the Vault Dweller confronts The Master and has three options. He can either:
 

• Convince The Master that the Super Mutant plan is horribly flawed, thus resulting in The Master committing suicide
• Fight The Master in normal combat
• Set off a nuclear bomb in the facility which kills The Master