administrator

One who administers affairs; one who directs, manages, executes, or dispenses, whether in civil, judicial, political, or ecclesiastical affairs; a manager

(law) A person who manages or settles the estate of an intestate, or of a testator when there is no competent executor; one to whom the right of administration has been committed by competent authority

(computing) One who is responsible for software installation, management, information and maintenance of a computer or network