There are seven Great Dragons in the world. Presumably the eldest, and thus strongest and wisest (or at least most intelligent), of dragons.
All are capable of flight except for Azarn and the Beast of Shasla. The Great Dragons have been actively hiding for the past two hundred years; the original triumvirate of Gor, Anaran and Azrad ordered all dragons to be slain (other than a small breeding stock).
(Details from newsgroup post <firstname.lastname@example.org> by Lawrence Watt-Evans on 08/07/2010 at 18:14 GMT)