- For information on Ultima VI: The False Prophet, see Ultima VI.
The False Prophet is what the Gargoyles thought the Avatar was -- until the end of Ultima VI proved the last part of their prophecy wrong. This prophecy of the end of the world, written in the Book of Prophecies, is as follows:
"An ancient prophecy tells of the final days, when the end of our world shall come.
Three signs shall precede the end.
Thrice shall a being of great evil come unto our land, and by this it shall be known that the end is nigh. This evil one is of another race, who consider the evil one a great prophet. Yet this false prophet follows not the principles of Control, Passion and Diligence.
One day the false prophet will come and desecrate our most holy shrine. And the false prophet will steal our most holy artefact, the Codex of Ultimate Wisdom. This shall be the first sign of the end.
Then it is written, the false prophet shall descend deep into the bowels of the earth. And the false prophet will cause the underworld to collapse. This will cause great earthquakes to tear our world asunder, and there will be a time of plague and famine. This shall be the second sign of the end.
One last time shall the false prophet come. This time the false prophet will come with a band of warriors. And they will destroy all that remains of the Gargoyle race.
There is only one way that this prophecy may be averted:
That is by the sacrifice of the false prophet."
Spoiler warning: Plot and/or ending details follow.
In Ultima IV, the Codex was discovered by the Stranger, but the Gargoyles were still an undiscovered species. It is strange that the Gargoyles came to accuse the Avatar of the Codex's theft, when in reality the members of the Great Council were responsible. In Ultima V, the clashing forces of the magical prison in dungeon Doom and the Orb of the Moons started the collapse of the underworld. Again, no one knew of the Gargoyles. By Ultima VI, the panicked Gargoyles fought for their survival. They thought killing the Avatar as a sacrifice would prevent the last sign from happening.
In the end, the prophecy was averted by the Avatar, by returning the Codex to the Void. From there, it showed both kings the truth, and in the following time, the Gargoyles were evacuated from their lands. The "sacrifice" that had to be made to avert the prophecy was actually the Codex itself, so that no one -- neither human nor gargoyle -- could possess it and claim it as his own.
Spoilers end here.