Mitchell Linehan was a pre-War American citizen who was accepted into Vault 114.
Living before the Great War, Mitchell, his mother Martha, his father Sean, and his brother John were all designated to live in Vault 114. Their family, the Linehans, were assigned to the Residency A1 section of the vault. However with Vault 114's unending construction they may not have been there when the bombs hit Boston.
Mitchell Linehan is mentioned only in Fallout 4.