[quote=http://riordan.wikia.com/wiki/Legacy]A legacy is any mortal who is a second or further generation descendant of a god. They tend to possess similar abilities to their godly ancestors, though their powers are usually diminished through each generation. Recognition of Legacies seems unique to Camp Jupiter. It is also stated that various emperors of Rome were Legacies. Only first generation descendants of the gods attend Camp Half-Blood, although Camp Jupiter accepts legacies.

There are probably more legacies than demigods in the world. Many demigods (not just Frank Zhang) are probably legacies as well as half-bloods.[/quote]