Gaius van Baelsar, also known as The Black Wolf, is one of the antagonists of Final Fantasy XIV. He is an Imperial Legatus of the Garlean Empire.
Gaius van Baelsar is a Hyur Legatus of the XIV Legion that is one of the Legions invading Eorzea. He uses a gunblade called the Heirsbane as his main weapon.
He can pilot ancient machina, notably the Ultima Weapon in the climax of the "A Realm Reborn" story.
In the 'A Realm Reborn' story, Gaius tells his Tribuni that Eorzea must be saved from the primals.
After the Warrior of Light defeats Garuda, Gaius appears. He kills the Ixal and uses the Ultima Weapon to absorb Ifrit, Titan, and Garuda.
During Operation Archon, he sends Rhitatyn sas Arvina and Livia sus Junius to Cape Westwind and Castrum Merdianum respectively, but both of them are killed in their battles against the Adventurer. When the Adventurer approaches to Gaius in the Praetorium, he praises his/her strength and fights him/her, After the first fight, he enters the Ultima Weapon and battles the Adventurer with the powers of the three primals. However, he gets defeated and loses the primals. Lahabrea appears, where he activates the true power of the Ultima Weapon. Gaius fights the Adventurer again. After the fight, his Ultima Weapon is destroyed. During the Adventurer's escape from the Praetorium, Gaius is killed by the explosions from the destruction of the Praetorium.