The Ozymandias of Shelley's poem is, ultimately, a testament to men's hubris. Such was his pride that Ozymandias declared himself "King of Kings" (an allusion to the Bible, in which the King of Kings is, of course, God, who stands alone in the Judeo-Christian reckoning). Having set himself up as a god among men, then, Ozymandias demands that onlookers "look on my works . . . and despair." The irony is that now there is nothing to look upon but bare sand, lending a different kind of despair to the words. Now, the onlooker is not despaired by Ozymandias's might but despaired instead by the fact that a man could be so proud and yet so mistaken: "nothing beside remains."
As a king, Ozymandias evidently wanted to portray himself as a figure of cold, almost cruel power: he has himself depicted with a "sneer of cold command," his statue wearing a "frown." And yet, there is now nothing left of his "works," and Ozymandias's attempts to elevate himself through cruelty to the realms of legend have come to naught.