dont know if these have been suggested but...
Minotaur- have one that might be all black with glowing eyes for Fury, and for Alliance have one thats brown with a halo or something above.
Snake- red,blue,green,black,white ect. maybe with a medusa head? class specific maybe?
Griffin- Alliance only? or maybe class specific.
Undead Animals- Scorpions, Gorillas, Wolf any kind u can think of with a poisonous aura around them. only Fury can get these. Epic drops?
If we are creating our own mounts tho i would want something with a gorilla like body and maybe a couple heads? One a lion, one a eagle, and maybe a third bein a bear.