Yes, one person may be executor, trustee, and beneficiary in a will. One person can often also serve as two of the three people in a trust agreement. That is, the same person can be the grantor and trustee, trustee and beneficiary, or grantor and beneficiary. It is even possible for the same person to be all three. The “person” does not even have to be a natural person. For example, the trustee can be the trust department of a bank and the beneficiary can be a charity.