O. Olivette

Dr. Olivette was the first overseer of Vault 81 and the only member of the "residential side" to know of the Vault's true purpose.

Background
When Vault 81 was built, it was designed with two parts: the residential side, where the vault dwellers would live, and the secret side, where scientists would conduct an experiment on the residents to create a cure for all of humanity's illnesses. Doctor O. Olivette was picked by Vault-Tec from their candidate list after their prime choice, Duncan, fell ill.

Dr. Olivette was skeptical of Vault-Tec's goal and possible use of human experimentation, planning to blow the whistle if it was unethical. However, when she received her full briefing, she found out the true unethical nature of the experiment, and Vault-Tec had major backers in the federal government, effectively eliminating the option of alerting the proper authorities. Dr Olivette was determined to not let the residents of the vault be used as guinea pigs, and on the morning of October 23, upon receiving the "call" to start the notification of staff and residents, she sabotaged the call list so the science staff wouldn't be notified and report in. Her plan mostly worked, however, three of the science staff turned up: two were living nearby, arriving with the general population, while the third showed up to check when the next drill was.

Dr. Olivette was the only person on the residential side aware of the existence of the secret Vault 81, which Olivette communicated with through terminal. As the three scientists worked to create their cure, Olivette watched over all of their data and personally had to approve the scientists moving onto to Phase II, animal testing, and Phase III, human testing on unknowing participants.

Before Phase III of testing began, Olivette disabled all access to the residential side of the vault, effectively isolating the scientists from entering the other side, leaving the three scientists to die. She kept the vault's true purpose, and the existence of the secret vault, a closely guarded secret.

Appearances
O. Olivette is only mentioned in Fallout 4.