Alien Empera (エンペラ星人, Enpera Seijin), also known as the Lord of Darkness and simply The Emperor, is the sole survivor of an alien race, having embraced the darkness to survive on his dying planet. He is the leader and ruler of the Empera Army and the commander of the Dark Four Heavenly Kings. Although originally mentioned in Ultraman Taro, he made his physical appearance in the four final episodes of Ultraman Mebius. He is one of the most powerful foes in the Ultraman Series to date, on par with his Armored Darkness. Despite his name, "Empera" is not the name of his race nor the name of his home planet.