Sargeras is the greatest evil of World of Warcraft universe. Once he was one of the Titans — the ancient creatures, who were created to bring order to the universe. Sargeras was the strongest of them and fought for Titans’ values bravely, imprisoning enemies of the Order, trying to put the end to the Havoc.
But the Havoc would not surrender, bringing even more obstacles to Sargeras’s path. And the bravest of the Titans started doubting whether he is right to fight the Havoc if the latter resists so restlessly. “Maybe it is the way that is supposed to be?” — Sargeras asked himself and his fellow Titans. But none of them brought him round. Sargeras’s mind was being corrupted until one day he turned into the deadliest enemy of the Order, setting free all the creatures he had imprisoned and turning them into his slaves.
That is how began the history of World of Warcraft. Thus Azeroth, home for humans, elves, tauren, and many other races, was put in jeopardy that has been lasting for many thousands of years by now.