A beneficiary is a person who, although not a party to a legal instrument, is expected to benefit from the existence of the legal instrument, either immediately, at a fixed future date, or when (and if) and event occurs in future. It is a common concept in trusts, insurance and in estate law.
As a general rule, if there is a person who controls a benefit that is, or will be, payable to a beneficiary, this relationship gives rise to a fiduciary duty to the person who controls the benefit. As such, this person must treat any assets under their control that may pass to the beneficiary in a manner consistent with the beneficiary's best interests.