The Four Horsemen of the Apocalypse were actually agents of the alien race known as the Axi-Tuns. They have been active for billions of earth years serving the empire. They conquered primitive Earth for about a century until another alien race that was more powerful than they were defeated them and banished them from our solar system. When they returned to the Axi-Tun Empire they were branded cowards and banished to wander the universe for all eternity. After roaming the universe for many centuries, they tried to reconquer the Earth but were opposed and defeated by the Fantastic Four. Somehow they were captured by The Stranger and were his prisoners in his laboratory, until the Overmind released them. They attacked Quasar who defeated them.