755 ILCS 5/1-2.11
"Interested person" in relation to any particular action, power or proceeding under this Act means one who has or represents a financial interest, property right or fiduciary status at the time of reference which may be affected by the action, power or proceeding involved, including without limitation an heir, legatee, creditor, person entitled to a spouse's or child's award and the representative. Whenever any provision of this Act requires notice or accounting to or action by an interested person, including without limitation Sections 24-2 and 28-11 of this Act, and a trustee of a trust is an interested person, no notice or accounting to or action by a beneficiary of the trust in his capacity as beneficiary shall be required. When a ward would be an interested person but a personal fiduciary is then acting for him pursuant to Section 28-3, the personal fiduciary is the interested person instead of the ward, but any notice required to be given to the ward under this Act shall be given to both the personal fiduciary and the ward. This definition also applies to the following terms: "interested party", "person (or party) interested" and "person (or party) in interest".
755 ILCS 5/1-2.11