Best Villian
Lex Luthor, Justice League Unlimited

And he nearly destroyed the world at the end.

Lex Luthor had always been Superman's most dangerous adversary. He presented himself as a valuable member of society on Superman: The Animated Series, but when he made his first full appearance on Justice League, he lost everything and got arrested for his crimes. Suffering from kryptonite poisoning, Luthor began wearing a battlesuit to shield off the radiation to keep him alive and to begin his revenge on Superman and the Justice League. He formed an "Injustice Gang" of villians to take on the League, but they failed miserably after Batman managed to get into the mind of Ultra-Humanite.

Luthor continued to pursue the Justice League on numerous occasions, but after he assisted Superman against the Justice Lords, an evil, alternate universe version of the Justice League, the evil businessman changed his stripes and was granted clemancy and a full pardon. Shortly after that, he made plans for the presidency of the United States, paralleling the situation that caused the Justice League to become the Justice Lords in the first place.

Years passed, and Candidate Luthor became a frontrunner for the presidency, much to the dismay of the Justice League. Meanwhile, after the Thanagarian invasion that sent longtime Justice League member Hawkgirl to leave, the Justice League rebuilt itself as an international organization with heroes all around the globe. While the Justice League were in space, a group of concerned citizens in the United States government began a clandestine mission to stop the subversive acts of these vigilantes. Collecting data on every metahuman and non-powered vigilante on the planet, The Cadmus Project began their mission. They supported the Ultimen, a group of young superheroes who just happened to be clones created by Cadmus and under the guidance of Maxwell Lord, who also made an impact in the DC Comics universe in 2005. This was the first time Cadmus was introduced to the League, and throughout the year, Cadmus confronted them. They created a "Suicide Squad" to steal a weapon from The Watchtower, unleashed their "Doomsday" creature to take on Superman (who nearly killed the hero), and unleashed Galatea, a clone of Supergirl who lead an army of Ultimen in a battle on the Watchtower. Even Captain Atom, a member of the Justice League, was enlisted by Cadmus to take on Superman.

Lex Luthor began a humanitarian mission by building a new urban community powered by a free energy source. When it was revealed that the power source was kryptonite, Sure enough, Superman was determined to destroy it. However, rookie Justice Leaguer Captain Marvel (who also publicly supported Lex Luthor) made sure that Superman couldn't do that. It was hero versus hero. And Lex Luthor planned every moment of it and revealed himself to be a member and financier of The Cadmus Project. Luthor used Cadmus technology to make The Watchtower destroy much of an East Coast city, causing the public to fear and distrust the Justice League. Cadmus was unaware of the plan set forth by Luthor, and was determined to distance themselves from him. However, it was too late as Lex Luthor revealed that he and the long-gone villian Brainiac were now one in the same. Powered by the ancient computer, Lex Luthor projected his own version of the Justice Lords to take on the core members of the Justice League. When they were defeated, Lex Luthor had plans to make the end of the world happen, which began after he kills The Flash. Needless to say, an unforseen event occurs forever changing the Justice League and Lex Luthor. Depowered and defeated, Lex Luthor went down, but not without impacting both Cadmus and Justice League's attitudes about each other and their place on the Earth.

By the end of the year, Lex Luthor was prison-bound, but a sinister plan was in the works courtesy of another enemy of the Justice League, who had their own ambitions for an event that could spell the end of the Justice League once and for all.