Ultima

Ultima is a name given in various Final Fantasy games to spells or creatures that roam the earth. In a couple of instances, Ultima refers to a powerful weapon for the lead character:

• Ultima's first appearance was in Final Fantasy II. It came late in the game, and would appear in future installments.
  

• Ultima returned in Final Fantasy VII, as both a Materia with the strongest spell on it, and as one of the weapons that roamed the planet of Gaia, called the Ultima Weapon. The Ultima Weapon is also the name of Cloud's strongest sword in the game.
• Ultima was again a very powerful but rare spell in Final Fantasy VIII. The best Draw Point was in Shumi Village, for a nominal fee that is. There was also an Ultima Weapon featured in FFVIII.

• Ultima was not a spell in Final Fantasy IX, but instead Trance Kuja's most powerful attack, which he unleashes on the party twice throughout the game, the second time basically killing them. Zidane's strongest sword is also the Ultima Weapon.
• Ultima returned to it's roots as a powerful spell, and Weapon in Final Fantasy X. It is Lulu's strongest Black Magic spell, but is found in Kimahri's section of the Sphere Grid. There is also Ultima Weapon, located in the Omega Ruins.