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 Arizona, 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 take over the role under circumstances such as the death, incapacity, resignation, or removal of the current trustee. The process for removal can involve court action initiated by the trust's beneficiaries. Trustees in Arizona are bound by a fiduciary duty, which is the highest standard of care in legal terms. This duty encompasses both the careful execution of the trust's terms and the avoidance of any conflicts of interest, ensuring that the trustee acts in the best interests of the beneficiaries. Arizona state statutes and case law provide the regulatory framework for the administration of trusts and the conduct of trustees.