Lord Zedd was the master of Evil in the quadrant, who left his servant Rita to the conquering of Earth while he launched attacks at other points in the galaxy. After numerous failures, Zedd returned to Earth, enraged at Rita's incompetence. He banished her into her dumpster yet again, and took over the battle against the Power Rangers. While he was an impressive villain for a while, it didn't take long before he fell to the wayside. There's something about attacking Earth that really ruins some perfectly good villains.