Imperial Griffon (WAR)  

This Exclusive mount is available only through the Warhammer Online Recruit-a-Friend Program. After recruiting or inviting players who have been gone for 60 days or more, Order players can receive the Imperial Griffon Mount.

They can't fly, but do grant a 70% movement speed bonus (compared to the 50% basic mount speed or the 60% of the Guild Rank 37 mounts).

Picture courtesy of The Official Warhammer Online Website

Warhammer Online Wikibase™