Obtaining: The Ebon Gryphon is an Alliance only mount and can be purchased for a small amount of gold at level 60 and above from a number of vendors, but two of the easier to get to vendors are:
1) Mei Francis
She stands right outside of the pet shop in both Legion and WotLK Dalaran cities.
He stands next to the flight master in Stormwind city.
Extra Tips: If you are below level 60 but wish to use these mounts then you can purchase them using a Class Trial and then will be able to use them on your lower level character as a ground mount and once you are the correct level also a flying mount.