Except for a few states where you are required to hire a real estate attorney to do your closing, you do not have to hire an agent or attorney to help you. Be aware, however, selling a home yourself is a lot of work. Beyond the obvious tasks normally provided by agents, such as advertising and marketing the house, preparing and showing up for open houses, and helping prepare documents and negotiate, good agents take care of a lot of behind-the-scenes tasks, like helping you decide which repairs need doing and getting recommendations on repair people, responding to questions by other agents or even unrepresented home buyers about the property, and even pulling out a mop when people at the open house are tracking in dirt.
Hiring an agent doesn't necessarily mean that he or she handles all aspects of the transaction and is paid the traditional 5-6% commission, however. Instead, to save money, you might consider hiring an agent to help you out in specific ways, such as advertising your home in the local multiple listing service (MLS) and handling some of the paperwork. For more information, see Nolo's article Do You Need a Real Estate Agent to Sell Your House? Or you might take care of most of the selling tasks yourself, and hire an attorney to help with the negotiations and closing paperwork.