A spouse is always considered a beneficiary. An unmarried cohabitant is always considered not a beneficiary.
Some states consider domestic partners to be beneficiaries.
Children are beneficiaries in the majority of states.
Step-children are not in the majority of states.
Some states require children born out of wedlock to be dependencies of the deceased.
Parents are usually only beneficiaries if a child dies without a spouse or children.
The next-of-kin is a beneficiary in some states if he can show a financial loss.