Gloria Mack is a resident of Vault 101 in Fallout 3. She is the daughter of Stanley Armstrong and the wife of Allen Mack. She can be seen during the Escape! quest sitting at a table with her head in her hands as Allen Mack bangs on the window and screams at you.
If you choose to help Amata become the new Vault Overseer during the Trouble on the Homefront quest, Gloria can sometimes be seen wandering the Capital Wasteland. Talk to her and she'll tell you that Amata allows people to leave the vault in order to trade supplies with other towns.