Xavier Montoya was a human male mentioned in the Babylon 5 episode Severed Dreams.
By 2260 Montoya was the leader of the Mars Provisional Government, following the planet wide violence that had taken place on Mars three years earlier and the reorganization of the Martian government.
In 2260 the tyrannical Earth Alliance President Morgan Clark declared martial law on Earth and ordered all EA ships, outposts, stations, and colonies to implement his martial law decree. Montoya, however, announced that he would not implement Clark's decree.
Clark decided to retaliate by ordering the bombing of civilian targets on Mars. This action led Babylon 5 and the colonies at Orion VII and Proxima III to break away from the Earth Alliance.
It is not known if Montoya was captured or killed following Clark's attack on Mars.