A trustee is a person or entity designated by a person who creates a trust (grantor, settlor, or trustor) to manage and administer the trust for the benefit of the named beneficiary or beneficiaries. The trustee of a trust created for estate planning purposes is often the grantor, settlor, or trustor who created and funded the trust.

A trust agreement may designate one or more successor trustees who will become the trustee if the previous trustee dies, is unable to continue to serve as trustee, resigns as trustee, or is removed by court order following a lawsuit filed by the beneficiary or beneficiaries of the trust.

A trustee has a fiduciary duty to the beneficiary or beneficiaries of the trust. A fiduciary duty includes the highest duty of care (performance of duties under the terms of the trust agreement) and of loyalty (avoiding conflicts of interest) recognized in law.

In Massachusetts, a trustee is responsible for managing a trust in accordance with the terms set forth by the grantor, who may also serve as the initial trustee in estate planning scenarios. Trust agreements typically outline provisions for successor trustees, who will take over the trustee's responsibilities in the event of death, incapacity, resignation, or removal of the current trustee. The process for the appointment of a successor trustee is usually detailed in the trust document itself. Trustees in Massachusetts are bound by a fiduciary duty to the trust's beneficiaries, which is the highest standard of care in legal and financial matters. This duty encompasses both a duty of care, ensuring that they manage the trust assets prudently and in accordance with the trust's terms, and a duty of loyalty, requiring them to act in the best interests of the beneficiaries and avoid conflicts of interest. If a trustee fails to uphold these duties, beneficiaries have the right to seek legal recourse, which can include the trustee's removal through a court order.