Ozymandias was a prince of ancient Egypt, 5000 years ago. He would have been king, except for the time-traveler calling himself Rama-Tut, who had advanced technology from the future, with which he seized control of the land. Ozymandias came into conflict with En Sabah Nur, a deformed slave who was the adopted son of the Stormriders' leader, Baal. The Stormriders were a nomadic band of warriors who were being hunted down by the Pharaoh at the time. When Nur's mutant powers manifested, and when he came upon some of Rama-Tut's technology, he transformed himself into Apocalypse. He punished Ozymandias for mistreating him and for killing his foster-father by genetically altering the prince so that his entire body became stone. Apocalypse also took the entire database from Rama-Tut's ship, containing tins of information about the future and forced it into Ozymandias's mind. Now blind, Ozymandias uses his "clairvoyance" to see what goes on in the world. His task is to record what he sees in stone, as a kind of hard copy of the history of mutantkind. At times he can see a short way into the future, and Apocalypse can always read his mind to see what he has seen, making Ozymandias a very convenient way of catching up after Apocalypse comes out of regeneration. Ozymandias can also animate his carvings and mentally direct them.
Years ago, before En Sabah Nur became Apocalypse using Celestial technology, Ozymandias watched as the Traveler (Cable) shot Apocalypse dead, thereby taking control of his Dark Riders. Ozymandias was charged by Traveler to do better things with his power. Some years afterwards, Ozymandias met Cable again and informed him that Apocalypse was able to regenerate using nanotech from Cable's own blood. He again watched as Cable fought Nur and sent him off into space for hundreds, if not thousands of years.
Following Apocalypse's return, Ozymandias also became the liason between the Clan Akkaba, the descendants of Apocalypse, and the High Lord during his periods of incubation. In the late 1800's Dracula began to attack the clan, and Ozymandias helped them wake Apocalypse. After Dracula's defeat and the destruction of the Clan, Ozymandias contradicted Apocalypse's orders and began to rebuild the Clan, specifically setting up teleporter Frederick Slade with a Ms. Ferguson to produce a mutant child.
Years later, Wolverine accidentally fell into Ozymandias's lair/workshop in North Africa, and the X-Men engaged him and his animated rock carvings in battle. There they got a glimpse of Onslaught, though they were unable to understand its full significance at the time.
During Apocalypse's proxy attack on New York using his Harbinger, Ozymandias was freed from his master's service. He then worked against Apocalypse, mostly by telling Blaquesmith bits of information that might aid his pupil Cable's fight against Apocalypse.
However, after Apocalypse's demise, Ozymandias gathered some of his blood and returned it to one of Apocalypse's strongholds, where it began to grow into a new body. It seems that while Apocalypse is regenerating, his allegiance shifts to Cable, who supports Apocalypse's returns so that he can defeat him again and again and prove his Darwinist theories wrong.
After Apocalypse returned following M-Day, however, Ozymandias chafed at his position even more, especially since Apocalypse appeared unwilling to follow through on his threats of mass extinction. He was tasked with refereeing the battle between Gazer and Dr. Foster to determine who would be the new War, but interfered and saved Gazer's life by killing Foster. Ozymandias expected to be repaid in loyalty after Gazer's transformation, but War IV declined and told Apocalypse of his servant's treachery. Ozymandias then came to the X-Men and led Havok's team into Apocalypse's Sphinx ship to confront his master. The X-Men failed to stop him completely, but Ozymandias refused to come with them, and retreated into the bowels of the ship. Later, as Apocalypse and his remaining Horsemen threatened the United Nations, and the X-Men and Avengers tried to stop them, Ozymandias appeared and stabbed Gazer through the chest from behind. He again found a way out before the ship sank, but where he went is unknown.