A trustee is someone given the legal responsibility to manage money, property, or other assets on behalf of someone else. When a wealthy person dies and leaves money for their young grandchildren, they might name a trustee to handle that money wisely until the children are old enough to manage it themselves. The trustee can't just spend the money however they want: they have a legal duty to use it only in ways that benefit the grandchildren.

The word comes from trust, because the trustee is someone trusted to do the right thing even when no one is watching. A school might have a board of trustees who oversee how the school operates and spends its money. A charity often has trustees who ensure donations are used properly for the charity's mission.

Being a trustee is serious business. If you're appointed trustee of your younger sibling's college fund, you can't use that money to buy yourself a new bike, even if you plan to “pay it back later.” A trustee who breaks this duty and misuses the assets they're managing can face serious legal consequences. The role requires both the competence to manage things well and integrity to always put the beneficiaries' interests first.