The Defender is a greatsword in Final Fantasy XII. Its license costs 70 LP. In the Zodiac versions, it can be used by Knight, White White Mage and Red Battlemage. White Mage needs to unlock Chaos on the License Board to reach it, and the Red Battlemage needs to unlock Ultima.
Defender is found in treasures (location depends on the version of the game; see below), bought from a shop in the original version, and a rarely dropped by Leynir. It is also a reward for the great cockatrice escape quest from helping out Moomer in the chocobo pen in the Sea Breeze Lane of Balfonheim Port. After the Miffed Moogle hires Moomer as a "chocobo," Gurdy will gift the party a Defender.