Fin Fang Foom

Fin Fang Foom is an alien from Maklu IV, whose race looks like, or perhaps is the inspiration for, dragons of legend.  FFF is impossibly old, sleeping for centuries at a time, occasionally being awakened from sleep by other parties, most recently the Mandarin. The Mandarin used his mind-control ring to control Fin Fang Foom, and used him as a weapon in his conquest of China.  Recently, Fin Fang Foom was released when the Mandarin attacked the Avengers, and during the battle the Wasp took the mind-control ring from the Mandarin's hand.