Trustee (or the holding of a trusteeship) is a legal term which, in its broadest sense, is a synonym for anyone in a position of trust and so can refer to any individual who holds property, authority, or a position of trust or responsibility for the benefit of another. A trustee can also be a person who is allowed to do certain tasks but not able to gain income. Although in the strictest sense of the term a trustee is the holder of property on behalf of a beneficiary, the more expansive sense encompasses persons who serve, for example, on the board of trustees of an institution that operates for a charity, for the benefit of the general public, or a person in the local government.

A trust can be set up either to benefit particular persons, or for any charitable purposes (but not generally for non-charitable purposes): typical examples are a will trust for the testator's children and family, a pension trust (to confer benefits on employees and their families) and a charitable trust. In all cases, the trustee may be a person or company, whether or not they are a prospective beneficiary.