Nightmare is a mount that can be summoned by the Nightmare Whistle. The whistle is dropped by Garuda (Extreme), Titan (Extreme), and Ifrit (Extreme).
While it is no secret that it was the enigmatic Ascians who provided the beast tribes with nightmares, their reasons for doing so remain shrouded in mystery. Otherwise untamable, the single piercing tone of a magicked whistle is the only method known to soothe the savage beasts.
Ahriman (Mount), Aithon, Behemoth (Mount), Bomb Palanquin, Boreas, Calvary Drake, Cavalry Elbst, Coeurl (Mount), Company Chocobo, Direwolf, Draught Chocobo, Enbarr, Fat Chocobo, Flame Warsteed, Gilded Magitek Armor, Goobbue (Mount), Gullfaxi, Laurel Goobbue, Legacy Chocobo, Magitek Armor (Mount), Markab, Nightmare, Serpent Warsteed, Sleipnir, Storm Warsteed, Unicorn, Warbear, Warlion, Xanthos