[abecedarius]

Plato was the opposite of a disinterested source on the trial of Socrates. The only other primary source is Xenophon, also his student. I wouldn't call Plato a propagandist, exactly, since that would imply writing on behalf of some organization or movement, but when I read him he seems a persuader in the guise of a truth-seeker. He's sort of the ur-Stephen Jay Gould.