Was Ozymandias a villain in the Watchmen, because he basically saved the world?

In the sense that he's the antagonist for the protagonists that we follow throughout the majority of the stories - yes, Veidt's a villain. His actions are complex, and whether his actions were ultimately good or evil are separate from whether or not he is a villain. Because he works to oppose the main characters through the duration of the story, he functions in a literary as a villain.