Wills
No matter how much or how little you think you may have, you still need a will to ensure that your assets are distributed as you wish. You will ensure that the person you desire will act to handle your estate. If you have children, you can also designate the person(s) you wish to be their guardian(s) should you die before they are adults.
Living Wills
A living will allows you to direct others as to whether you wish to be artificially provided food and liquid should you become incapacitated (force fed). It also allows you to designate which, if any, organs you wish to donate.