No, you don't need a receiver. At least not a conventional one. Your options include an all in one system referred to as a Home Theater in a Box system. Some of those do actually use a receiver, some do not. The ones that don't have a receiver use a control console(basically a receiver) that sometimes includes a DVD player or Blu Ray player in one unit. Either way they include all the basic functions of a receiver.
Another option for some is to use whats called a "soundbar". These things give you simulated suround sound without having to position speakers around your room. Sound bars come in 2 flavors: powered and passive. The passive ones will require you to use a receiver, the powered ones do not. Again, the powered soundbars will have most of the functions of a receiver such as source selection and amplification. They usually have enough inputs to be adequate for someone looking for a modest system.