In a legal context, a "beneficiary" usually refers to the person for whom a trust has been created.
May also be referred to as a "donee" or, for legal tecchies, as a cestui que trust.
Trusts are made to advantage a beneficiary.
For example, a settlor (also called a "donor") transfers property to a trustee who manages the property, the profits of which are to go to the beneficiairy.
In estate law, the term is synonymous with heir or heirs.
Whether by will or intestate, the beneficiaries of an estate trust are those persons to whom, ultimately, the property is going. After death, there is a necessary lull as authority must be granted by the Court for the distribution of the estate.
One of the primary functions of the trustee of an estate, also known as a personal administrator (either an executor or an administrator) is to collect and catalogue (inventory) all the assets of the deceased and then to proceed with distribution to the beneficiaries.
If there is a willl, these beneficiaries are as set out in the will.
If the estate is intestate, the beneficiaries will be as detailed and listed in the relevant statute of each jurisdiction which will set out the respective shares of the estate depending who the surviving relatives of the deceased are such as a spouse, children, siblings, grand-children, cousins etc., sometimes on a declining scale.
For example, in California, the distribution of a person who died intestate is set out in that state's Probate Code (as of 2007), ¶6400 onwards.
In Canada's common law provinces (all but Quebec), each province has a distinct intestate succession statute (eg. Alberta, see references below) or a dedicated part within their estate administration statute (eg. BC).
References:
• California's Probate Code, available at leginfo.ca.gov
• Intestate Succession Act, 2000 RSA (Alberta) Chapter I-10 at canlii.com/ab/laws/sta/i-10/