Trust Protector and Trust Advisor
A Trust Protector is a disinterested, nonbeneficiary, third party who provides protection to the trust from an uncooperative trustee or from changes in circumstance (such as giving a gift to a certain number of grandkids and another grandchild is born). The trust protector's role is defined in the trust and may be limited or broadly written. For example, the trust protector may be given the right to have a trustee removed, if the trustee is not following through with their duties.
Similarly, a Trust Advisor makes sure the terms of the trust are carried out, but they are more focused on the beneficiary side and the advisement of the trustee. The advisor's main role is making sure the beneficiary's rights are being upheld. This is usually done by a professional with a certified trust and financial advisor designation.