Tiamat

Notes:
 * Spawns around E-9 every 3-5 days. (36-72hr after maintenance)
 * Around 100,000HP.
 * Killable by: At least 10 level 75 characters. However, more people will be required depending on how experienced with the fight the players are. A full alliance of 18 plus an add party for fighting potential links is recommended.
 * Fairly susceptible to both Water and Thunder elements.
 * Special Attacks: Draw In, Mighty Strikes (multiple times), Auto Regen (low), Blaze Spikes, and Firaga III.
 * Tiamat uses the wing attack Tebbad Wing, which afflicts anyone hit with Plague.
 * Tiamat gains a large attack boost when health is under 25% which cannot be Dispelled.
 * Tiamat's Horrid Roar dispels all buffs including food and resets enmity.
 * Tiamat's AoE abilities can be blocked by terrain differences if she is fought near the rock at the entrance of her spawn area.
 * Tiamat lands and flies on two-minute intervals. However, a phase change will be forced after 10,000 damage is dealt, regardless of the time spent in its current phase. (Note: If Mighty Strikes is active while Tiamat is on the ground, it will not fly under any circumstances until the duration of Mighty Strikes has expired.)
 * Tiamat's air attacks are fire based. Because of this, it is recommended that your tanks have fire resist, or Magic Defense sets.
 * There are many aggressive monsters in the area, including Cave Antlions, Air Elementals, Earth Elementals, Bifrons and Arch Corses. It is recommended to have an outside party to control these.
 * Tiamat can cast Firaga III while in the air and on the ground, therefore a Dark Knight, Black Mage, or other job capable of a reliable, long-distance Stun is recommended.

Historical Background
In Mesopotamian mythology, Tiamat (Tiamat (Babylonian), Tamtu (Sumerian)) is a giant female dragon which was the primordial creatrix of all existence. She created the world and the gods, though this world had no land and was a vast water-world, filled with the waters of chaos. Tiamat personified the saltwater (ocean) while her consort Apsu (Apsu (Babylonian), Abzu (Sumerian)) personified the 'sweetwater' (freshwater). The intermingling of these two waters created the gods. In the Enuma Elish (the Mesopotamian creation epic), the gods bother Tiamat & Apsu, so the two decide to kill all their children. The god Ea discovers their plan and preemptively slays Apsu or casts a spell that puts him in a death-like sleep (since the waters of Apsu still exist even after his 'death'). Tiamat then sought revenge by creating an army of monsters and a new consort, Kingu (alt. Qingu) to be their general. Tiamat was slain by Marduk who trapped her with a "net of winds", shot arrows down her throat, and then cleaved her body in two, with the upper half creating the heavens and the sky and the lower half creating the earth. Tiamat is Akkadian for "sea".

Dungeons & Dragons (one of the inspirations for the original Final Fantasy) used Tiamat as an evil dragon goddess, specifically a 5-headed dragon (one black, one red, one green, one white, one blue). This is likely where Square got the idea to place her in Final Fantasy I.