Getting the Centurio Tiger mount is cakewalk compared to fully upgrading a relic or mythic weapon back in the primetime days of FFXI ;P lol

The 2 mentioned though are probably the closest in game right now to what I assume must be a ghostly looking tiger. However take a peek at the item database and look at mounts. You'll probably find something to tug on your heart strings and a direction on how to get it.