There are four main characters for a trust. 
I. The person who starts it all is the grantor.  This is the person who sets up the trust.  Usually it will be you. 

II. The person who officially manages the trust is called the trustee.  The trustee is a person who will do everything necessary to manage the assets in the trust.  Usually this will be done also by the grantor, or sometimes by you while you are alive.  For most married couples, the husband and the wife can act as co trustees.  Of course you can get someone else to be the trustee if you do not want to perform the service; and there are many good strategic reason why you would want to do this.

III. It is prudent to designate a successor trustee.  This is the person who will manage the assets in the trust when the trustee and the grantor dies or becomes incapacitated.  After the grantor and the trustee, the successor trustee becomes the trustee and has all the powers to manage the trust.  However, the successor trustee does not have the legal right to change a trust, unless this is specifically provided for in the trust. 

IV. Finally, the ones who can receive the benefits for the trust are called the beneficiaries.  These are named individuals who will receive the benefit of the trust and assets.  Typically the assets in the trust will go to a surviving spouse, or if there is no surviving spouse then to your other loved ones such as your child and family members.