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 South Dakota, a trustee is responsible for managing a trust in accordance with the terms set forth by the grantor and in the best interests of the beneficiaries. The trustee's role includes a fiduciary duty, which is the highest standard of care in managing the trust's assets and avoiding conflicts of interest. South Dakota trust laws allow for the designation of successor trustees who can step in under circumstances such as the death, incapacity, resignation, or removal of the current trustee. The process for removal of a trustee typically involves court proceedings, which can be initiated by the beneficiaries if they believe the trustee is not fulfilling their fiduciary duties. South Dakota's trust laws are designed to provide a flexible framework for estate planning, and the state is known for its favorable trust laws, including perpetual trusts and asset protection trusts.