To leave a legacy behind means to leave something behind that made a big impact to the world. For example a legacy I believe that my grandmother left was that she is working hard for the community that we live in because she is trying to make sure that all the kids in our community stay out of trouble and stay in school so they can make something good of their life. 

Also I believe you do not have to be famous to leave a mark on the world because anyone can leave a legacy behind if they only do what they believe is right for the world. For example a person can leave a legacy behind if he or she starts a petition to help sick animals, or if people try to help find a cure for cancer. Anyone could try to do those things and they do not have to be famous to accomplish those task. 

To me I think you do not have to be famous to leave behind a legacy because you can just do what you believe is right and you do not have to be famous to do anything right. That is why I think you do not have to be famous to leave behind a legacy because any man or woman can leave behind a legacy and they do not have to be famous to do so.