Someone who appears in court in place of another who is not competent to do so, usually because they are a minor or are considered incompetent. Often the role is filled by a parent or other relative; it can be any legally-competent person whose interests do not run counter to those of the person on whose behalf they are acting . The “next friend” is not a party to the proceeding, nor are they a formally-appointed guardian. Instead, they are considered an agent of the court whose role is to protect the rights of the incompetent person. See also guardian ad litem.
Legal Information Institute